Merge branch 'master' into activestorage-guide

90 files changed, 1175 insertions, 363 deletions

diff --git a/.codeclimate.yml b/.codeclimate.yml
index 1f0f067c5b..d59a0780d1 100644
--- a/.codeclimate.yml
+++ b/.codeclimate.yml
@@ -1,3 +1,25 @@
+checks:
+  argument-count:
+    enabled: false
+  complex-logic:
+    enabled: false
+  file-lines:
+    enabled: false
+  method-complexity:
+    enabled: false
+  method-count:
+    enabled: false
+  method-lines:
+    enabled: false
+  nested-control-flow:
+    enabled: false
+  return-statements:
+    enabled: false
+  similar-code:
+    enabled: false
+  identical-code:
+    enabled: false
+
 engines:
   rubocop:
     enabled: true
diff --git a/.travis.yml b/.travis.yml
index 290e0b5f2b..fd3b3f9002 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,10 +20,6 @@ addons:
     sources:
       - sourceline: "ppa:mc3man/trusty-media"
       - sourceline: "ppa:ubuntuhandbook1/apps"
-    packages:
-      - ffmpeg
-      - mupdf
-      - mupdf-tools
 
 bundler_args: --without test --jobs 3 --retry 3
 before_install:
@@ -42,6 +38,7 @@ before_script:
   # Decodes to e.g. `export VARIABLE=VALUE`
   - $(base64 --decode <<< "ZXhwb3J0IFNBVUNFX0FDQ0VTU19LRVk9YTAzNTM0M2YtZTkyMi00MGIzLWFhM2MtMDZiM2VhNjM1YzQ4")
   - $(base64 --decode <<< "ZXhwb3J0IFNBVUNFX1VTRVJOQU1FPXJ1YnlvbnJhaWxz")
+  - if [[ $GEM = *ast*  ]] ; then sudo apt-get update && sudo apt-get -y install ffmpeg mupdf mupdf-tools ; fi
 
 script: 'ci/travis.rb'
 
diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index c8fb34ed52..753dd8589a 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,3 +1,19 @@
+*   Add headless firefox support to System Tests.
+
+    *bogdanvlviv*
+
+*   Changed the default system test screenshot output from `inline` to `simple`.
+
+    `inline` works well for iTerm2 but not everyone uses iTerm2. Some terminals like
+    Terminal.app ignore the `inline` and output the path to the file since it can't
+    render the image. Other terminals, like those on Ubuntu, cannot handle the image
+    inline, but also don't handle it gracefully and instead of outputting the file
+    path, it dumps binary into the terminal.
+
+    Commit 9d6e28 fixes this by changing the default for screenshot to be `simple`.
+
+    *Eileen M. Uchitelle*
+
 *   Register most popular audio/video/font mime types supported by modern browsers.
 
     *Guillermo Iguaran*
diff --git a/actionpack/lib/action_controller/metal/request_forgery_protection.rb b/actionpack/lib/action_controller/metal/request_forgery_protection.rb
index 04fadc90e2..767eddb361 100644
--- a/actionpack/lib/action_controller/metal/request_forgery_protection.rb
+++ b/actionpack/lib/action_controller/metal/request_forgery_protection.rb
@@ -415,11 +415,21 @@ module ActionController #:nodoc:
         allow_forgery_protection
       end
 
+      NULL_ORIGIN_MESSAGE = <<-MSG.strip_heredoc
+        The browser returned a 'null' origin for a request with origin-based forgery protection turned on. This usually
+        means you have the 'no-referrer' Referrer-Policy header enabled, or that you the request came from a site that
+        refused to give its origin. This makes it impossible for Rails to verify the source of the requests. Likely the
+        best solution is to change your referrer policy to something less strict like same-origin or strict-same-origin.
+        If you cannot change the referrer policy, you can disable origin checking with the
+        Rails.application.config.action_controller.forgery_protection_origin_check setting.
+      MSG
+
       # Checks if the request originated from the same origin by looking at the
       # Origin header.
       def valid_request_origin? # :doc:
         if forgery_protection_origin_check
           # We accept blank origin headers because some user agents don't send it.
+          raise InvalidAuthenticityToken, NULL_ORIGIN_MESSAGE if request.origin == "null"
           request.origin.nil? || request.origin == request.base_url
         else
           true
diff --git a/actionpack/lib/action_controller/metal/strong_parameters.rb b/actionpack/lib/action_controller/metal/strong_parameters.rb
index ef7c4c4c16..a56ac749f8 100644
--- a/actionpack/lib/action_controller/metal/strong_parameters.rb
+++ b/actionpack/lib/action_controller/metal/strong_parameters.rb
@@ -335,7 +335,7 @@ module ActionController
     # the same way as <tt>Hash#each_pair</tt>.
     def each_pair(&block)
       @parameters.each_pair do |key, value|
-        yield key, convert_hashes_to_parameters(key, value)
+        yield [key, convert_hashes_to_parameters(key, value)]
       end
     end
     alias_method :each, :each_pair
diff --git a/actionpack/lib/action_dispatch/http/content_security_policy.rb b/actionpack/lib/action_dispatch/http/content_security_policy.rb
index d10d4faf3d..4883e23d24 100644
--- a/actionpack/lib/action_dispatch/http/content_security_policy.rb
+++ b/actionpack/lib/action_dispatch/http/content_security_policy.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "active_support/core_ext/object/deep_dup"
+
 module ActionDispatch #:nodoc:
   class ContentSecurityPolicy
     class Middleware
@@ -110,7 +112,7 @@ module ActionDispatch #:nodoc:
     end
 
     def initialize_copy(other)
-      @directives = copy_directives(other.directives)
+      @directives = other.directives.deep_dup
     end
 
     DIRECTIVES.each do |name, directive|
@@ -174,10 +176,6 @@ module ActionDispatch #:nodoc:
     end
 
     private
-      def copy_directives(directives)
-        directives.transform_values { |sources| sources.map(&:dup) }
-      end
-
       def apply_mappings(sources)
         sources.map do |source|
           case source
diff --git a/actionpack/lib/action_dispatch/system_test_case.rb b/actionpack/lib/action_dispatch/system_test_case.rb
index 7246e01cff..99d0c06751 100644
--- a/actionpack/lib/action_dispatch/system_test_case.rb
+++ b/actionpack/lib/action_dispatch/system_test_case.rb
@@ -121,11 +121,15 @@ module ActionDispatch
     #
     #   driven_by :poltergeist
     #
-    #   driven_by :selenium, using: :firefox
+    #   driven_by :selenium, screen_size: [800, 800]
+    #
+    #   driven_by :selenium, using: :chrome
     #
     #   driven_by :selenium, using: :headless_chrome
     #
-    #   driven_by :selenium, screen_size: [800, 800]
+    #   driven_by :selenium, using: :firefox
+    #
+    #   driven_by :selenium, using: :headless_firefox
     def self.driven_by(driver, using: :chrome, screen_size: [1400, 1400], options: {})
       self.driver = SystemTesting::Driver.new(driver, using: using, screen_size: screen_size, options: options)
     end
diff --git a/actionpack/lib/action_dispatch/system_testing/driver.rb b/actionpack/lib/action_dispatch/system_testing/driver.rb
index 2687772b4b..280989a146 100644
--- a/actionpack/lib/action_dispatch/system_testing/driver.rb
+++ b/actionpack/lib/action_dispatch/system_testing/driver.rb
@@ -38,13 +38,24 @@ module ActionDispatch
             browser_options.args << "--disable-gpu"
 
             @options.merge(options: browser_options)
+          elsif @browser == :headless_firefox
+            browser_options = Selenium::WebDriver::Firefox::Options.new
+            browser_options.args << "-headless"
+
+            @options.merge(options: browser_options)
           else
             @options
           end
         end
 
         def browser
-          @browser == :headless_chrome ? :chrome : @browser
+          if @browser == :headless_chrome
+            :chrome
+          elsif @browser == :headless_firefox
+            :firefox
+          else
+            @browser
+          end
         end
 
         def register_selenium(app)
diff --git a/actionpack/test/abstract_unit.rb b/actionpack/test/abstract_unit.rb
index 5262e85a28..55ad9c245e 100644
--- a/actionpack/test/abstract_unit.rb
+++ b/actionpack/test/abstract_unit.rb
@@ -453,3 +453,7 @@ end
 class DrivenBySeleniumWithHeadlessChrome < ActionDispatch::SystemTestCase
   driven_by :selenium, using: :headless_chrome
 end
+
+class DrivenBySeleniumWithHeadlessFirefox < ActionDispatch::SystemTestCase
+  driven_by :selenium, using: :headless_firefox
+end
diff --git a/actionpack/test/controller/parameters/accessors_test.rb b/actionpack/test/controller/parameters/accessors_test.rb
index 43cabae7d2..154430d4b0 100644
--- a/actionpack/test/controller/parameters/accessors_test.rb
+++ b/actionpack/test/controller/parameters/accessors_test.rb
@@ -51,6 +51,14 @@ class ParametersAccessorsTest < ActiveSupport::TestCase
     @params.each { |key, value| assert_not(value.permitted?) if key == "person" }
   end
 
+  test "each returns key,value array for block with arity 1" do
+    @params.each do |arg|
+      assert_kind_of Array, arg
+      assert_equal "person", arg[0]
+      assert_kind_of ActionController::Parameters, arg[1]
+    end
+  end
+
   test "each_pair carries permitted status" do
     @params.permit!
     @params.each_pair { |key, value| assert(value.permitted?) if key == "person" }
@@ -60,6 +68,14 @@ class ParametersAccessorsTest < ActiveSupport::TestCase
     @params.each_pair { |key, value| assert_not(value.permitted?) if key == "person" }
   end
 
+  test "each_pair returns key,value array for block with arity 1" do
+    @params.each_pair do |arg|
+      assert_kind_of Array, arg
+      assert_equal "person", arg[0]
+      assert_kind_of ActionController::Parameters, arg[1]
+    end
+  end
+
   test "empty? returns true when params contains no key/value pairs" do
     params = ActionController::Parameters.new
     assert params.empty?
diff --git a/actionpack/test/controller/request_forgery_protection_test.rb b/actionpack/test/controller/request_forgery_protection_test.rb
index eb3d2f34a8..4822d85bcb 100644
--- a/actionpack/test/controller/request_forgery_protection_test.rb
+++ b/actionpack/test/controller/request_forgery_protection_test.rb
@@ -446,6 +446,19 @@ module RequestForgeryProtectionTests
     end
   end
 
+  def test_should_raise_for_post_with_null_origin
+    forgery_protection_origin_check do
+      session[:_csrf_token] = @token
+      @controller.stub :form_authenticity_token, @token do
+        exception = assert_raises(ActionController::InvalidAuthenticityToken) do
+          @request.set_header "HTTP_ORIGIN", "null"
+          post :index, params: { custom_authenticity_token: @token }
+        end
+        assert_match "The browser returned a 'null' origin for a request", exception.message
+      end
+    end
+  end
+
   def test_should_block_post_with_origin_checking_and_wrong_origin
     old_logger = ActionController::Base.logger
     logger = ActiveSupport::LogSubscriber::TestHelper::MockLogger.new
diff --git a/actionpack/test/controller/routing_test.rb b/actionpack/test/controller/routing_test.rb
index f09051b306..71b01c36a7 100644
--- a/actionpack/test/controller/routing_test.rb
+++ b/actionpack/test/controller/routing_test.rb
@@ -213,7 +213,7 @@ class LegacyRouteSetTests < ActiveSupport::TestCase
     assert_equal expected, ActiveSupport::JSON.decode(get(u))
   end
 
-  def test_regexp_precidence
+  def test_regexp_precedence
     rs.draw do
       get "/whois/:domain", constraints: {
         domain: /\w+\.[\w\.]+/ },
diff --git a/actionpack/test/dispatch/content_security_policy_test.rb b/actionpack/test/dispatch/content_security_policy_test.rb
index 8a1ac066e8..7c4a65a633 100644
--- a/actionpack/test/dispatch/content_security_policy_test.rb
+++ b/actionpack/test/dispatch/content_security_policy_test.rb
@@ -14,6 +14,15 @@ class ContentSecurityPolicyTest < ActiveSupport::TestCase
     assert_equal "script-src 'self';", @policy.build
   end
 
+  def test_dup
+    @policy.img_src :self
+    @policy.block_all_mixed_content
+    @policy.upgrade_insecure_requests
+    @policy.sandbox
+    copied = @policy.dup
+    assert_equal copied.build, @policy.build
+  end
+
   def test_mappings
     @policy.script_src :data
     assert_equal "script-src data:;", @policy.build
diff --git a/actionpack/test/dispatch/session/cookie_store_test.rb b/actionpack/test/dispatch/session/cookie_store_test.rb
index 2c43a8c29f..e34426a471 100644
--- a/actionpack/test/dispatch/session/cookie_store_test.rb
+++ b/actionpack/test/dispatch/session/cookie_store_test.rb
@@ -8,11 +8,14 @@ require "active_support/messages/rotation_configuration"
 class CookieStoreTest < ActionDispatch::IntegrationTest
   SessionKey = "_myapp_session"
   SessionSecret = "b3c631c314c0bbca50c1b2843150fe33"
-  Generator = ActiveSupport::LegacyKeyGenerator.new(SessionSecret)
+  SessionSalt   = "authenticated encrypted cookie"
+
+  Generator = ActiveSupport::KeyGenerator.new(SessionSecret, iterations: 1000)
   Rotations = ActiveSupport::Messages::RotationConfiguration.new
 
-  Verifier = ActiveSupport::MessageVerifier.new(SessionSecret, digest: "SHA1")
-  SignedBar = Verifier.generate(foo: "bar", session_id: SecureRandom.hex(16))
+  Encryptor = ActiveSupport::MessageEncryptor.new(
+    Generator.generate_key(SessionSalt, 32), cipher: "aes-256-gcm", serializer: Marshal
+  )
 
   class TestController < ActionController::Base
     def no_session_access
@@ -25,12 +28,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
 
     def set_session_value
       session[:foo] = "bar"
-      render plain: Rack::Utils.escape(Verifier.generate(session.to_hash))
-    end
-
-    def set_session_value_expires_in_five_hours
-      session[:foo] = "bar"
-      render plain: Rack::Utils.escape(Verifier.generate(session.to_hash, expires_in: 5.hours))
+      render body: nil
     end
 
     def get_session_value
@@ -72,19 +70,35 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
     end
   end
 
+  def parse_cookie_from_header
+    cookie_matches = headers["Set-Cookie"].match(/#{SessionKey}=([^;]+)/)
+    cookie_matches && cookie_matches[1]
+  end
+
+  def assert_session_cookie(cookie_string, contents)
+    assert_includes headers["Set-Cookie"], cookie_string
+
+    session_value = parse_cookie_from_header
+    session_data = Encryptor.decrypt_and_verify(Rack::Utils.unescape(session_value)) rescue nil
+
+    assert_not_nil session_data, "session failed to decrypt"
+    assert_equal session_data.slice(*contents.keys), contents
+  end
+
   def test_setting_session_value
     with_test_route_set do
       get "/set_session_value"
+
       assert_response :success
-      assert_equal "_myapp_session=#{response.body}; path=/; HttpOnly",
-        headers["Set-Cookie"]
+      assert_session_cookie "path=/; HttpOnly", "foo" => "bar"
     end
   end
 
   def test_getting_session_value
     with_test_route_set do
-      cookies[SessionKey] = SignedBar
+      get "/set_session_value"
       get "/get_session_value"
+
       assert_response :success
       assert_equal 'foo: "bar"', response.body
     end
@@ -92,8 +106,9 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
 
   def test_getting_session_id
     with_test_route_set do
-      cookies[SessionKey] = SignedBar
+      get "/set_session_value"
       get "/persistent_session_id"
+
       assert_response :success
       assert_equal 32, response.body.size
       session_id = response.body
@@ -106,8 +121,12 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
 
   def test_disregards_tampered_sessions
     with_test_route_set do
-      cookies[SessionKey] = "BAh7BjoIZm9vIghiYXI%3D--123456780"
+      encryptor = ActiveSupport::MessageEncryptor.new("A" * 32, cipher: "aes-256-gcm", serializer: Marshal)
+
+      cookies[SessionKey] = encryptor.encrypt_and_sign("foo" => "bar", "session_id" => "abc")
+
       get "/get_session_value"
+
       assert_response :success
       assert_equal "foo: nil", response.body
     end
@@ -135,19 +154,19 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
   def test_does_set_secure_cookies_over_https
     with_test_route_set(secure: true) do
       get "/set_session_value", headers: { "HTTPS" => "on" }
+
       assert_response :success
-      assert_equal "_myapp_session=#{response.body}; path=/; secure; HttpOnly",
-        headers["Set-Cookie"]
+      assert_session_cookie "path=/; secure; HttpOnly", "foo" => "bar"
     end
   end
 
   # {:foo=>#<SessionAutoloadTest::Foo bar:"baz">, :session_id=>"ce8b0752a6ab7c7af3cdb8a80e6b9e46"}
-  SignedSerializedCookie = "BAh7BzoIZm9vbzodU2Vzc2lvbkF1dG9sb2FkVGVzdDo6Rm9vBjoJQGJhciIIYmF6Og9zZXNzaW9uX2lkIiVjZThiMDc1MmE2YWI3YzdhZjNjZGI4YTgwZTZiOWU0Ng==--2bf3af1ae8bd4e52b9ac2099258ace0c380e601c"
+  EncryptedSerializedCookie = "9RZ2Fij0qLveUwM4s+CCjGqhpjyUC8jiBIf/AiBr9M3TB8xh2vQZtvSOMfN3uf6oYbbpIDHAcOFIEl69FcW1ozQYeSrCLonYCazoh34ZdYskIQfGwCiSYleVXG1OD9Z4jFqeVArw4Ewm0paOOPLbN1rc6A==--I359v/KWdZ1ok0ey--JFFhuPOY7WUo6tB/eP05Aw=="
 
   def test_deserializes_unloaded_classes_on_get_id
     with_test_route_set do
       with_autoload_path "session_autoload_test" do
-        cookies[SessionKey] = SignedSerializedCookie
+        cookies[SessionKey] = EncryptedSerializedCookie
         get "/get_session_id"
         assert_response :success
         assert_equal "id: ce8b0752a6ab7c7af3cdb8a80e6b9e46", response.body, "should auto-load unloaded class"
@@ -158,7 +177,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
   def test_deserializes_unloaded_classes_on_get_value
     with_test_route_set do
       with_autoload_path "session_autoload_test" do
-        cookies[SessionKey] = SignedSerializedCookie
+        cookies[SessionKey] = EncryptedSerializedCookie
         get "/get_session_value"
         assert_response :success
         assert_equal 'foo: #<SessionAutoloadTest::Foo bar:"baz">', response.body, "should auto-load unloaded class"
@@ -197,8 +216,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
       get "/set_session_value"
       assert_response :success
       session_payload = response.body
-      assert_equal "_myapp_session=#{response.body}; path=/; HttpOnly",
-        headers["Set-Cookie"]
+      assert_session_cookie "path=/; HttpOnly", "foo" => "bar"
 
       get "/call_reset_session"
       assert_response :success
@@ -216,8 +234,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
     with_test_route_set do
       get "/set_session_value"
       assert_response :success
-      assert_equal "_myapp_session=#{response.body}; path=/; HttpOnly",
-        headers["Set-Cookie"]
+      assert_session_cookie "path=/; HttpOnly", "foo" => "bar"
 
       get "/get_class_after_reset_session"
       assert_response :success
@@ -239,8 +256,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
     with_test_route_set do
       get "/set_session_value"
       assert_response :success
-      assert_equal "_myapp_session=#{response.body}; path=/; HttpOnly",
-        headers["Set-Cookie"]
+      assert_session_cookie "path=/; HttpOnly", "foo" => "bar"
 
       get "/call_session_clear"
       assert_response :success
@@ -253,7 +269,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
 
   def test_persistent_session_id
     with_test_route_set do
-      cookies[SessionKey] = SignedBar
+      get "/set_session_value"
       get "/persistent_session_id"
       assert_response :success
       assert_equal 32, response.body.size
@@ -268,8 +284,7 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
 
   def test_setting_session_id_to_nil_is_respected
     with_test_route_set do
-      cookies[SessionKey] = SignedBar
-
+      get "/set_session_value"
       get "/get_session_id"
       sid = response.body
       assert_equal 36, sid.size
@@ -283,31 +298,53 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
     with_test_route_set(expire_after: 5.hours) do
       # First request accesses the session
       time = Time.local(2008, 4, 24)
+
       Time.stub :now, time do
         expected_expiry = (time + 5.hours).gmtime.strftime("%a, %d %b %Y %H:%M:%S -0000")
 
-        cookies[SessionKey] = SignedBar
+        get "/set_session_value"
 
-        get "/set_session_value_expires_in_five_hours"
         assert_response :success
-
-        cookie_body = response.body
-        assert_equal "_myapp_session=#{cookie_body}; path=/; expires=#{expected_expiry}; HttpOnly",
-          headers["Set-Cookie"]
+        assert_session_cookie "path=/; expires=#{expected_expiry}; HttpOnly", "foo" => "bar"
       end
 
       # Second request does not access the session
-      time = Time.local(2008, 4, 25)
+      time = time + 3.hours
       Time.stub :now, time do
         expected_expiry = (time + 5.hours).gmtime.strftime("%a, %d %b %Y %H:%M:%S -0000")
 
-        cookies[SessionKey] = SignedBar
-
         get "/no_session_access"
+
         assert_response :success
+        assert_session_cookie "path=/; expires=#{expected_expiry}; HttpOnly", "foo" => "bar"
+      end
+    end
+  end
+
+  def test_session_store_with_expire_after_does_not_accept_expired_session
+    with_test_route_set(expire_after: 5.hours) do
+      # First request accesses the session
+      time = Time.local(2017, 11, 12)
+
+      Time.stub :now, time do
+        expected_expiry = (time + 5.hours).gmtime.strftime("%a, %d %b %Y %H:%M:%S -0000")
 
-        assert_equal "_myapp_session=#{cookies[SessionKey]}; path=/; expires=#{expected_expiry}; HttpOnly",
-          headers["Set-Cookie"]
+        get "/set_session_value"
+        get "/get_session_value"
+
+        assert_response :success
+        assert_equal 'foo: "bar"', response.body
+        assert_session_cookie "path=/; expires=#{expected_expiry}; HttpOnly", "foo" => "bar"
+      end
+
+      # Second request is beyond the expiry time and the session is invalidated
+      time += 5.hours + 1.minute
+
+      Time.stub :now, time do
+        get "/get_session_value"
+
+        assert_response :success
+        assert_equal "foo: nil", response.body
       end
     end
   end
@@ -347,8 +384,14 @@ class CookieStoreTest < ActionDispatch::IntegrationTest
     def get(path, *args)
       args[0] ||= {}
       args[0][:headers] ||= {}
-      args[0][:headers]["action_dispatch.key_generator"] ||= Generator
-      args[0][:headers]["action_dispatch.cookies_rotations"] ||= Rotations
+      args[0][:headers].tap do |config|
+        config["action_dispatch.secret_key_base"] = SessionSecret
+        config["action_dispatch.authenticated_encrypted_cookie_salt"] = SessionSalt
+        config["action_dispatch.use_authenticated_cookie_encryption"] = true
+
+        config["action_dispatch.key_generator"] ||= Generator
+        config["action_dispatch.cookies_rotations"] ||= Rotations
+      end
 
       super(path, *args)
     end
diff --git a/actionpack/test/dispatch/system_testing/driver_test.rb b/actionpack/test/dispatch/system_testing/driver_test.rb
index 75feae6fe0..fcdaf7fb4c 100644
--- a/actionpack/test/dispatch/system_testing/driver_test.rb
+++ b/actionpack/test/dispatch/system_testing/driver_test.rb
@@ -25,6 +25,14 @@ class DriverTest < ActiveSupport::TestCase
     assert_equal ({ url: "http://example.com/wd/hub" }), driver.instance_variable_get(:@options)
   end
 
+  test "initializing the driver with a headless firefox" do
+    driver = ActionDispatch::SystemTesting::Driver.new(:selenium, using: :headless_firefox, screen_size: [1400, 1400], options: { url: "http://example.com/wd/hub" })
+    assert_equal :selenium, driver.instance_variable_get(:@name)
+    assert_equal :headless_firefox, driver.instance_variable_get(:@browser)
+    assert_equal [1400, 1400], driver.instance_variable_get(:@screen_size)
+    assert_equal ({ url: "http://example.com/wd/hub" }), driver.instance_variable_get(:@options)
+  end
+
   test "initializing the driver with a poltergeist" do
     driver = ActionDispatch::SystemTesting::Driver.new(:poltergeist, screen_size: [1400, 1400], options: { js_errors: false })
     assert_equal :poltergeist, driver.instance_variable_get(:@name)
diff --git a/actionpack/test/dispatch/system_testing/system_test_case_test.rb b/actionpack/test/dispatch/system_testing/system_test_case_test.rb
index c6a6aef92b..b078a5abc5 100644
--- a/actionpack/test/dispatch/system_testing/system_test_case_test.rb
+++ b/actionpack/test/dispatch/system_testing/system_test_case_test.rb
@@ -28,6 +28,12 @@ class SetDriverToSeleniumHeadlessChromeTest < DrivenBySeleniumWithHeadlessChrome
   end
 end
 
+class SetDriverToSeleniumHeadlessFirefoxTest < DrivenBySeleniumWithHeadlessFirefox
+  test "uses selenium headless firefox" do
+    assert_equal :selenium, Capybara.current_driver
+  end
+end
+
 class SetHostTest < DrivenByRackTest
   test "sets default host" do
     assert_equal "http://127.0.0.1", Capybara.app_host
diff --git a/actionview/CHANGELOG.md b/actionview/CHANGELOG.md
index 566e30993b..f42ada0baa 100644
--- a/actionview/CHANGELOG.md
+++ b/actionview/CHANGELOG.md
@@ -1,7 +1,7 @@
 *   Add `preload_link_tag` helper
 
     This helper that allows to the browser to initiate early fetch of resources
-    (different to the specified in javascript_include_tag and stylesheet_link_tag).
+    (different to the specified in `javascript_include_tag` and `stylesheet_link_tag`).
     Additionally, this sends Early Hints if supported by browser.
 
     *Guillermo Iguaran*
diff --git a/activejob/lib/active_job/core.rb b/activejob/lib/active_job/core.rb
index c4e12fc518..879746fc01 100644
--- a/activejob/lib/active_job/core.rb
+++ b/activejob/lib/active_job/core.rb
@@ -97,17 +97,23 @@ module ActiveJob
     # ==== Examples
     #
     #    class DeliverWebhookJob < ActiveJob::Base
+    #      attr_writer :attempt_number
+    #
+    #      def attempt_number
+    #        @attempt_number ||= 0
+    #      end
+    #
     #      def serialize
-    #        super.merge('attempt_number' => (@attempt_number || 0) + 1)
+    #        super.merge('attempt_number' => attempt_number + 1)
     #      end
     #
     #      def deserialize(job_data)
     #        super
-    #        @attempt_number = job_data['attempt_number']
+    #        self.attempt_number = job_data['attempt_number']
     #      end
     #
-    #      rescue_from(TimeoutError) do |exception|
-    #        raise exception if @attempt_number > 5
+    #      rescue_from(Timeout::Error) do |exception|
+    #        raise exception if attempt_number > 5
     #        retry_job(wait: 10)
     #      end
     #    end
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 60ceffac5e..89a12d4223 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,11 @@
+*   Add support for PostgreSQL operator classes to `add_index`.
+
+    Example:
+
+        add_index :users, :name, using: :gist, opclass: { name: :gist_trgm_ops }
+
+    *Greg Navis*
+
 *   Don't allow scopes to be defined which conflict with instance methods on `Relation`.
 
     Fixes #31120.
@@ -72,7 +80,7 @@
     *bogdanvlviv*
 
 *   Fixed a bug where column orders for an index weren't written to
-    db/schema.rb when using the sqlite adapter.
+    `db/schema.rb` when using the sqlite adapter.
 
     Fixes #30902.
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index be2f625d74..0594b4b485 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -6,7 +6,7 @@ module ActiveRecord
     # this type are typically created and returned by methods in database
     # adapters. e.g. ActiveRecord::ConnectionAdapters::MySQL::SchemaStatements#indexes
     class IndexDefinition # :nodoc:
-      attr_reader :table, :name, :unique, :columns, :lengths, :orders, :where, :type, :using, :comment
+      attr_reader :table, :name, :unique, :columns, :lengths, :orders, :opclasses, :where, :type, :using, :comment
 
       def initialize(
         table, name,
@@ -14,6 +14,7 @@ module ActiveRecord
         columns = [],
         lengths: {},
         orders: {},
+        opclasses: {},
         where: nil,
         type: nil,
         using: nil,
@@ -23,13 +24,23 @@ module ActiveRecord
         @name = name
         @unique = unique
         @columns = columns
-        @lengths = lengths
-        @orders = orders
+        @lengths = concise_options(lengths)
+        @orders = concise_options(orders)
+        @opclasses = concise_options(opclasses)
         @where = where
         @type = type
         @using = using
         @comment = comment
       end
+
+      private
+        def concise_options(options)
+          if columns.size == options.size && options.values.uniq.size == 1
+            options.values.first
+          else
+            options
+          end
+        end
     end
 
     # Abstract representation of a column definition. Instances of this type
@@ -85,6 +96,11 @@ module ActiveRecord
         options[:primary_key] != default_primary_key
       end
 
+      def validate?
+        options.fetch(:validate, true)
+      end
+      alias validated? validate?
+
       def defined_for?(to_table_ord = nil, to_table: nil, **options)
         if to_table_ord
           self.to_table == to_table_ord.to_s
@@ -204,6 +220,7 @@ module ActiveRecord
         :decimal,
         :float,
         :integer,
+        :json,
         :string,
         :text,
         :time,
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 9b7345f7c3..4f58b0242c 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -600,7 +600,7 @@ module ActiveRecord
       # to provide these in a migration's +change+ method so it can be reverted.
       # In that case, +type+ and +options+ will be used by #add_column.
       def remove_column(table_name, column_name, type = nil, options = {})
-        execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{quote_column_name(column_name)}"
+        execute "ALTER TABLE #{quote_table_name(table_name)} #{remove_column_for_alter(table_name, column_name, type, options)}"
       end
 
       # Changes the column's definition according to the new options.
@@ -738,6 +738,28 @@ module ActiveRecord
       #
       # Note: only supported by PostgreSQL and MySQL
       #
+      # ====== Creating an index with a specific operator class
+      #
+      #   add_index(:developers, :name, using: 'gist', opclass: :gist_trgm_ops)
+      #
+      # generates:
+      #
+      #   CREATE INDEX developers_on_name ON developers USING gist (name gist_trgm_ops) -- PostgreSQL
+      #
+      #   add_index(:developers, [:name, :city], using: 'gist', opclass: { city: :gist_trgm_ops })
+      #
+      # generates:
+      #
+      #   CREATE INDEX developers_on_name_and_city ON developers USING gist (name, city gist_trgm_ops) -- PostgreSQL
+      #
+      #   add_index(:developers, [:name, :city], using: 'gist', opclass: :gist_trgm_ops)
+      #
+      # generates:
+      #
+      #   CREATE INDEX developers_on_name_and_city ON developers USING gist (name gist_trgm_ops, city gist_trgm_ops) -- PostgreSQL
+      #
+      # Note: only supported by PostgreSQL
+      #
       # ====== Creating an index with a specific type
       #
       #   add_index(:developers, :name, type: :fulltext)
@@ -942,6 +964,8 @@ module ActiveRecord
       #   Action that happens <tt>ON DELETE</tt>. Valid values are +:nullify+, +:cascade+ and +:restrict+
       # [<tt>:on_update</tt>]
       #   Action that happens <tt>ON UPDATE</tt>. Valid values are +:nullify+, +:cascade+ and +:restrict+
+      # [<tt>:validate</tt>]
+      #   (Postgres only) Specify whether or not the constraint should be validated. Defaults to +true+.
       def add_foreign_key(from_table, to_table, options = {})
         return unless supports_foreign_keys?
 
@@ -1120,7 +1144,7 @@ module ActiveRecord
       def add_index_options(table_name, column_name, comment: nil, **options) # :nodoc:
         column_names = index_column_names(column_name)
 
-        options.assert_valid_keys(:unique, :order, :name, :where, :length, :internal, :using, :algorithm, :type)
+        options.assert_valid_keys(:unique, :order, :name, :where, :length, :internal, :using, :algorithm, :type, :opclass)
 
         index_type = options[:type].to_s if options.key?(:type)
         index_type ||= options[:unique] ? "UNIQUE" : ""
@@ -1173,20 +1197,22 @@ module ActiveRecord
         end
 
         def add_index_sort_order(quoted_columns, **options)
-          if order = options[:order]
-            case order
-            when Hash
-              order = order.symbolize_keys
-              quoted_columns.each { |name, column| column << " #{order[name].upcase}" if order[name].present? }
-            when String
-              quoted_columns.each { |name, column| column << " #{order.upcase}" if order.present? }
-            end
+          orders = options_for_index_columns(options[:order])
+          quoted_columns.each do |name, column|
+            column << " #{orders[name].upcase}" if orders[name].present?
           end
+        end
 
-          quoted_columns
+        def options_for_index_columns(options)
+          if options.is_a?(Hash)
+            options.symbolize_keys
+          else
+            Hash.new { |hash, column| hash[column] = options }
+          end
         end
 
-        # Overridden by the MySQL adapter for supporting index lengths
+        # Overridden by the MySQL adapter for supporting index lengths and by
+        # the PostgreSQL adapter for supporting operator classes.
         def add_options_for_index_columns(quoted_columns, **options)
           if supports_index_sort_order?
             quoted_columns = add_index_sort_order(quoted_columns, options)
@@ -1340,6 +1366,20 @@ module ActiveRecord
           options.is_a?(Hash) && options.key?(:name) && options.except(:name, :algorithm).empty?
         end
 
+        def add_column_for_alter(table_name, column_name, type, options = {})
+          td = create_table_definition(table_name)
+          cd = td.new_column_definition(column_name, type, options)
+          schema_creation.accept(AddColumnDefinition.new(cd))
+        end
+
+        def remove_column_for_alter(table_name, column_name, type = nil, options = {})
+          "DROP COLUMN #{quote_column_name(column_name)}"
+        end
+
+        def remove_columns_for_alter(table_name, *column_names)
+          column_names.map { |column_name| remove_column_for_alter(table_name, column_name) }
+        end
+
         def insert_versions_sql(versions)
           sm_table = quote_table_name(ActiveRecord::SchemaMigration.table_name)
 
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 8993c517a6..fc80d332f9 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -272,6 +272,11 @@ module ActiveRecord
         false
       end
 
+      # Does this adapter support creating invalid constraints?
+      def supports_validate_constraints?
+        false
+      end
+
       # Does this adapter support creating foreign key constraints
       # in the same statement as creating the table?
       def supports_foreign_keys_in_create?
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index ede8a9c1e2..479131caad 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -299,7 +299,7 @@ module ActiveRecord
       def bulk_change_table(table_name, operations) #:nodoc:
         sqls = operations.flat_map do |command, args|
           table, arguments = args.shift, args
-          method = :"#{command}_sql"
+          method = :"#{command}_for_alter"
 
           if respond_to?(method, true)
             send(method, table, *arguments)
@@ -372,11 +372,11 @@ module ActiveRecord
       end
 
       def change_column(table_name, column_name, type, options = {}) #:nodoc:
-        execute("ALTER TABLE #{quote_table_name(table_name)} #{change_column_sql(table_name, column_name, type, options)}")
+        execute("ALTER TABLE #{quote_table_name(table_name)} #{change_column_for_alter(table_name, column_name, type, options)}")
       end
 
       def rename_column(table_name, column_name, new_column_name) #:nodoc:
-        execute("ALTER TABLE #{quote_table_name(table_name)} #{rename_column_sql(table_name, column_name, new_column_name)}")
+        execute("ALTER TABLE #{quote_table_name(table_name)} #{rename_column_for_alter(table_name, column_name, new_column_name)}")
         rename_column_indexes(table_name, column_name, new_column_name)
       end
 
@@ -605,25 +605,6 @@ module ActiveRecord
           end
         end
 
-        def add_index_length(quoted_columns, **options)
-          if length = options[:length]
-            case length
-            when Hash
-              length = length.symbolize_keys
-              quoted_columns.each { |name, column| column << "(#{length[name]})" if length[name].present? }
-            when Integer
-              quoted_columns.each { |name, column| column << "(#{length})" }
-            end
-          end
-
-          quoted_columns
-        end
-
-        def add_options_for_index_columns(quoted_columns, **options)
-          quoted_columns = add_index_length(quoted_columns, options)
-          super
-        end
-
         # See https://dev.mysql.com/doc/refman/5.7/en/error-messages-server.html
         ER_DUP_ENTRY            = 1062
         ER_NOT_NULL_VIOLATION   = 1048
@@ -671,13 +652,7 @@ module ActiveRecord
           end
         end
 
-        def add_column_sql(table_name, column_name, type, options = {})
-          td = create_table_definition(table_name)
-          cd = td.new_column_definition(column_name, type, options)
-          schema_creation.accept(AddColumnDefinition.new(cd))
-        end
-
-        def change_column_sql(table_name, column_name, type, options = {})
+        def change_column_for_alter(table_name, column_name, type, options = {})
           column = column_for(table_name, column_name)
           type ||= column.sql_type
 
@@ -698,7 +673,7 @@ module ActiveRecord
           schema_creation.accept(ChangeColumnDefinition.new(cd, column.name))
         end
 
-        def rename_column_sql(table_name, column_name, new_column_name)
+        def rename_column_for_alter(table_name, column_name, new_column_name)
           column  = column_for(table_name, column_name)
           options = {
             default: column.default,
@@ -712,31 +687,23 @@ module ActiveRecord
           schema_creation.accept(ChangeColumnDefinition.new(cd, column.name))
         end
 
-        def remove_column_sql(table_name, column_name, type = nil, options = {})
-          "DROP #{quote_column_name(column_name)}"
-        end
-
-        def remove_columns_sql(table_name, *column_names)
-          column_names.map { |column_name| remove_column_sql(table_name, column_name) }
-        end
-
-        def add_index_sql(table_name, column_name, options = {})
+        def add_index_for_alter(table_name, column_name, options = {})
           index_name, index_type, index_columns, _, index_algorithm, index_using = add_index_options(table_name, column_name, options)
           index_algorithm[0, 0] = ", " if index_algorithm.present?
           "ADD #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})#{index_algorithm}"
         end
 
-        def remove_index_sql(table_name, options = {})
+        def remove_index_for_alter(table_name, options = {})
           index_name = index_name_for_remove(table_name, options)
           "DROP INDEX #{quote_column_name(index_name)}"
         end
 
-        def add_timestamps_sql(table_name, options = {})
-          [add_column_sql(table_name, :created_at, :datetime, options), add_column_sql(table_name, :updated_at, :datetime, options)]
+        def add_timestamps_for_alter(table_name, options = {})
+          [add_column_for_alter(table_name, :created_at, :datetime, options), add_column_for_alter(table_name, :updated_at, :datetime, options)]
         end
 
-        def remove_timestamps_sql(table_name, options = {})
-          [remove_column_sql(table_name, :updated_at), remove_column_sql(table_name, :created_at)]
+        def remove_timestamps_for_alter(table_name, options = {})
+          [remove_column_for_alter(table_name, :updated_at), remove_column_for_alter(table_name, :created_at)]
         end
 
         # MySQL is too stupid to create a temporary table for use subquery, so we have
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
index da25e4863c..2ed4ad16ae 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_definitions.rb
@@ -32,10 +32,6 @@ module ActiveRecord
           args.each { |name| column(name, :longtext, options) }
         end
 
-        def json(*args, **options)
-          args.each { |name| column(name, :json, options) }
-        end
-
         def unsigned_integer(*args, **options)
           args.each { |name| column(name, :unsigned_integer, options) }
         end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
index a15c7d1787..ce50590651 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
@@ -22,23 +22,26 @@ module ActiveRecord
                   index_using = mysql_index_type
                 end
 
-                indexes << IndexDefinition.new(
+                indexes << [
                   row[:Table],
                   row[:Key_name],
                   row[:Non_unique].to_i == 0,
+                  [],
+                  lengths: {},
+                  orders: {},
                   type: index_type,
                   using: index_using,
                   comment: row[:Index_comment].presence
-                )
+                ]
               end
 
-              indexes.last.columns << row[:Column_name]
-              indexes.last.lengths.merge!(row[:Column_name] => row[:Sub_part].to_i) if row[:Sub_part]
-              indexes.last.orders.merge!(row[:Column_name] => :desc) if row[:Collation] == "D"
+              indexes.last[-2] << row[:Column_name]
+              indexes.last[-1][:lengths].merge!(row[:Column_name] => row[:Sub_part].to_i) if row[:Sub_part]
+              indexes.last[-1][:orders].merge!(row[:Column_name] => :desc) if row[:Collation] == "D"
             end
           end
 
-          indexes
+          indexes.map { |index| IndexDefinition.new(*index) }
         end
 
         def remove_column(table_name, column_name, type = nil, options = {})
@@ -103,6 +106,18 @@ module ActiveRecord
             super unless specifier == "RESTRICT"
           end
 
+          def add_index_length(quoted_columns, **options)
+            lengths = options_for_index_columns(options[:length])
+            quoted_columns.each do |name, column|
+              column << "(#{lengths[name]})" if lengths[name].present?
+            end
+          end
+
+          def add_options_for_index_columns(quoted_columns, **options)
+            quoted_columns = add_index_length(quoted_columns, options)
+            super
+          end
+
           def data_source_sql(name = nil, type: nil)
             scope = quoted_scope(name, type: type)
 
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb
index 59f661da25..8e381a92cf 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb
@@ -5,6 +5,18 @@ module ActiveRecord
     module PostgreSQL
       class SchemaCreation < AbstractAdapter::SchemaCreation # :nodoc:
         private
+          def visit_AlterTable(o)
+            super << o.constraint_validations.map { |fk| visit_ValidateConstraint fk }.join(" ")
+          end
+
+          def visit_AddForeignKey(o)
+            super.dup.tap { |sql| sql << " NOT VALID" unless o.validate? }
+          end
+
+          def visit_ValidateConstraint(name)
+            "VALIDATE CONSTRAINT #{quote_column_name(name)}"
+          end
+
           def add_column_options!(sql, options)
             if options[:collation]
               sql << " COLLATE \"#{options[:collation]}\""
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
index 75622eb304..6047217fcd 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
@@ -95,10 +95,6 @@ module ActiveRecord
           args.each { |name| column(name, :int8range, options) }
         end
 
-        def json(*args, **options)
-          args.each { |name| column(name, :json, options) }
-        end
-
         def jsonb(*args, **options)
           args.each { |name| column(name, :jsonb, options) }
         end
@@ -192,6 +188,19 @@ module ActiveRecord
       class Table < ActiveRecord::ConnectionAdapters::Table
         include ColumnMethods
       end
+
+      class AlterTable < ActiveRecord::ConnectionAdapters::AlterTable
+        attr_reader :constraint_validations
+
+        def initialize(td)
+          super
+          @constraint_validations = []
+        end
+
+        def validate_constraint(name)
+          @constraint_validations << name
+        end
+      end
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 846e721983..bf5fbb30e1 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -87,10 +87,7 @@ module ActiveRecord
 
           result = query(<<-SQL, "SCHEMA")
             SELECT distinct i.relname, d.indisunique, d.indkey, pg_get_indexdef(d.indexrelid), t.oid,
-                            pg_catalog.obj_description(i.oid, 'pg_class') AS comment,
-            (SELECT COUNT(*) FROM pg_opclass o
-               JOIN (SELECT unnest(string_to_array(d.indclass::text, ' '))::int oid) c
-                 ON o.oid = c.oid WHERE o.opcdefault = 'f')
+                            pg_catalog.obj_description(i.oid, 'pg_class') AS comment
             FROM pg_class t
             INNER JOIN pg_index d ON t.oid = d.indrelid
             INNER JOIN pg_class i ON d.indexrelid = i.oid
@@ -109,11 +106,13 @@ module ActiveRecord
             inddef = row[3]
             oid = row[4]
             comment = row[5]
-            opclass = row[6]
 
             using, expressions, where = inddef.scan(/ USING (\w+?) \((.+?)\)(?: WHERE (.+))?\z/).flatten
 
-            if indkey.include?(0) || opclass > 0
+            orders = {}
+            opclasses = {}
+
+            if indkey.include?(0)
               columns = expressions
             else
               columns = Hash[query(<<-SQL.strip_heredoc, "SCHEMA")].values_at(*indkey).compact
@@ -123,10 +122,12 @@ module ActiveRecord
                 AND a.attnum IN (#{indkey.join(",")})
               SQL
 
-              # add info on sort order for columns (only desc order is explicitly specified, asc is the default)
-              orders = Hash[
-                expressions.scan(/(\w+) DESC/).flatten.map { |order_column| [order_column, :desc] }
-              ]
+              # add info on sort order (only desc order is explicitly specified, asc is the default)
+              # and non-default opclasses
+              expressions.scan(/(\w+)(?: (?!DESC)(\w+))?(?: (DESC))?/).each do |column, opclass, desc|
+                opclasses[column] = opclass.to_sym if opclass
+                orders[column] = :desc if desc
+              end
             end
 
             IndexDefinition.new(
@@ -135,6 +136,7 @@ module ActiveRecord
               unique,
               columns,
               orders: orders,
+              opclasses: opclasses,
               where: where,
               using: using.to_sym,
               comment: comment.presence
@@ -392,50 +394,23 @@ module ActiveRecord
 
         def change_column(table_name, column_name, type, options = {}) #:nodoc:
           clear_cache!
-          quoted_table_name = quote_table_name(table_name)
-          quoted_column_name = quote_column_name(column_name)
-          sql_type = type_to_sql(type, options)
-          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}".dup
-          if options[:collation]
-            sql << " COLLATE \"#{options[:collation]}\""
-          end
-          if options[:using]
-            sql << " USING #{options[:using]}"
-          elsif options[:cast_as]
-            cast_as_type = type_to_sql(options[:cast_as], options)
-            sql << " USING CAST(#{quoted_column_name} AS #{cast_as_type})"
-          end
-          execute sql
-
-          change_column_default(table_name, column_name, options[:default]) if options.key?(:default)
-          change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
-          change_column_comment(table_name, column_name, options[:comment]) if options.key?(:comment)
+          sqls, procs = change_column_for_alter(table_name, column_name, type, options)
+          execute "ALTER TABLE #{quote_table_name(table_name)} #{sqls.join(", ")}"
+          procs.each(&:call)
         end
 
         # Changes the default value of a table column.
         def change_column_default(table_name, column_name, default_or_changes) # :nodoc:
-          clear_cache!
-          column = column_for(table_name, column_name)
-          return unless column
-
-          default = extract_new_default_value(default_or_changes)
-          alter_column_query = "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} %s"
-          if default.nil?
-            # <tt>DEFAULT NULL</tt> results in the same behavior as <tt>DROP DEFAULT</tt>. However, PostgreSQL will
-            # cast the default to the columns type, which leaves us with a default like "default NULL::character varying".
-            execute alter_column_query % "DROP DEFAULT"
-          else
-            execute alter_column_query % "SET DEFAULT #{quote_default_expression(default, column)}"
-          end
+          execute "ALTER TABLE #{quote_table_name(table_name)} #{change_column_default_for_alter(table_name, column_name, default_or_changes)}"
         end
 
         def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
           clear_cache!
           unless null || default.nil?
             column = column_for(table_name, column_name)
-            execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote_default_expression(default, column)} WHERE #{quote_column_name(column_name)} IS NULL") if column
+            execute "UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote_default_expression(default, column)} WHERE #{quote_column_name(column_name)} IS NULL" if column
           end
-          execute("ALTER TABLE #{quote_table_name(table_name)} ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL")
+          execute "ALTER TABLE #{quote_table_name(table_name)} #{change_column_null_for_alter(table_name, column_name, null, default)}"
         end
 
         # Adds comment for given table column or drops it if +comment+ is a +nil+
@@ -458,8 +433,8 @@ module ActiveRecord
         end
 
         def add_index(table_name, column_name, options = {}) #:nodoc:
-          index_name, index_type, index_columns, index_options, index_algorithm, index_using, comment = add_index_options(table_name, column_name, options)
-          execute("CREATE #{index_type} INDEX #{index_algorithm} #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} #{index_using} (#{index_columns})#{index_options}").tap do
+          index_name, index_type, index_columns_and_opclasses, index_options, index_algorithm, index_using, comment = add_index_options(table_name, column_name, options)
+          execute("CREATE #{index_type} INDEX #{index_algorithm} #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} #{index_using} (#{index_columns_and_opclasses})#{index_options}").tap do
             execute "COMMENT ON INDEX #{quote_column_name(index_name)} IS #{quote(comment)}" if comment
           end
         end
@@ -499,7 +474,7 @@ module ActiveRecord
         def foreign_keys(table_name)
           scope = quoted_scope(table_name)
           fk_info = exec_query(<<-SQL.strip_heredoc, "SCHEMA")
-            SELECT t2.oid::regclass::text AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confupdtype AS on_update, c.confdeltype AS on_delete
+            SELECT t2.oid::regclass::text AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confupdtype AS on_update, c.confdeltype AS on_delete, c.convalidated AS valid
             FROM pg_constraint c
             JOIN pg_class t1 ON c.conrelid = t1.oid
             JOIN pg_class t2 ON c.confrelid = t2.oid
@@ -521,6 +496,7 @@ module ActiveRecord
 
             options[:on_delete] = extract_foreign_key_action(row["on_delete"])
             options[:on_update] = extract_foreign_key_action(row["on_update"])
+            options[:validate] = row["valid"]
 
             ForeignKeyDefinition.new(table_name, row["to_table"], options)
           end
@@ -581,6 +557,43 @@ module ActiveRecord
           PostgreSQL::SchemaDumper.create(self, options)
         end
 
+        # Validates the given constraint.
+        #
+        # Validates the constraint named +constraint_name+ on +accounts+.
+        #
+        #   validate_constraint :accounts, :constraint_name
+        def validate_constraint(table_name, constraint_name)
+          return unless supports_validate_constraints?
+
+          at = create_alter_table table_name
+          at.validate_constraint constraint_name
+
+          execute schema_creation.accept(at)
+        end
+
+        # Validates the given foreign key.
+        #
+        # Validates the foreign key on +accounts.branch_id+.
+        #
+        #   validate_foreign_key :accounts, :branches
+        #
+        # Validates the foreign key on +accounts.owner_id+.
+        #
+        #   validate_foreign_key :accounts, column: :owner_id
+        #
+        # Validates the foreign key named +special_fk_name+ on the +accounts+ table.
+        #
+        #   validate_foreign_key :accounts, name: :special_fk_name
+        #
+        # The +options+ hash accepts the same keys as SchemaStatements#add_foreign_key.
+        def validate_foreign_key(from_table, options_or_to_table = {})
+          return unless supports_validate_constraints?
+
+          fk_name_to_validate = foreign_key_for!(from_table, options_or_to_table).name
+
+          validate_constraint from_table, fk_name_to_validate
+        end
+
         private
           def schema_creation
             PostgreSQL::SchemaCreation.new(self)
@@ -590,6 +603,10 @@ module ActiveRecord
             PostgreSQL::TableDefinition.new(*args)
           end
 
+          def create_alter_table(name)
+            PostgreSQL::AlterTable.new create_table_definition(name)
+          end
+
           def new_column_from_field(table_name, field)
             column_name, type, default, notnull, oid, fmod, collation, comment = field
             type_metadata = fetch_type_metadata(column_name, type, oid.to_i, fmod.to_i)
@@ -629,6 +646,66 @@ module ActiveRecord
             end
           end
 
+          def change_column_sql(table_name, column_name, type, options = {})
+            quoted_column_name = quote_column_name(column_name)
+            sql_type = type_to_sql(type, options)
+            sql = "ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}".dup
+            if options[:collation]
+              sql << " COLLATE \"#{options[:collation]}\""
+            end
+            if options[:using]
+              sql << " USING #{options[:using]}"
+            elsif options[:cast_as]
+              cast_as_type = type_to_sql(options[:cast_as], options)
+              sql << " USING CAST(#{quoted_column_name} AS #{cast_as_type})"
+            end
+
+            sql
+          end
+
+          def change_column_for_alter(table_name, column_name, type, options = {})
+            sqls = [change_column_sql(table_name, column_name, type, options)]
+            procs = []
+            sqls << change_column_default_for_alter(table_name, column_name, options[:default]) if options.key?(:default)
+            sqls << change_column_null_for_alter(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
+            procs << Proc.new { change_column_comment(table_name, column_name, options[:comment]) } if options.key?(:comment)
+
+            [sqls, procs]
+          end
+
+
+          # Changes the default value of a table column.
+          def change_column_default_for_alter(table_name, column_name, default_or_changes) # :nodoc:
+            column = column_for(table_name, column_name)
+            return unless column
+
+            default = extract_new_default_value(default_or_changes)
+            alter_column_query = "ALTER COLUMN #{quote_column_name(column_name)} %s"
+            if default.nil?
+              # <tt>DEFAULT NULL</tt> results in the same behavior as <tt>DROP DEFAULT</tt>. However, PostgreSQL will
+              # cast the default to the columns type, which leaves us with a default like "default NULL::character varying".
+              alter_column_query % "DROP DEFAULT"
+            else
+              alter_column_query % "SET DEFAULT #{quote_default_expression(default, column)}"
+            end
+          end
+
+          def change_column_null_for_alter(table_name, column_name, null, default = nil) #:nodoc:
+            "ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL"
+          end
+
+          def add_index_opclass(quoted_columns, **options)
+            opclasses = options_for_index_columns(options[:opclass])
+            quoted_columns.each do |name, column|
+              column << " #{opclasses[name]}" if opclasses[name].present?
+            end
+          end
+
+          def add_options_for_index_columns(quoted_columns, **options)
+            quoted_columns = add_index_opclass(quoted_columns, options)
+            super
+          end
+
           def data_source_sql(name = nil, type: nil)
             scope = quoted_scope(name, type: type)
             scope[:type] ||= "'r','v','m'" # (r)elation/table, (v)iew, (m)aterialized view
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 27011bfe92..23fc69d649 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -142,6 +142,10 @@ module ActiveRecord
         true
       end
 
+      def supports_validate_constraints?
+        true
+      end
+
       def supports_views?
         true
       end
@@ -386,7 +390,6 @@ module ActiveRecord
       end
 
       private
-
         # See https://www.postgresql.org/docs/current/static/errcodes-appendix.html
         VALUE_LIMIT_VIOLATION = "22001"
         NUMERIC_VALUE_OUT_OF_RANGE = "22003"
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index daece2bffd..c72db15ce3 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -70,7 +70,8 @@ module ActiveRecord
         time:         { name: "time" },
         date:         { name: "date" },
         binary:       { name: "blob" },
-        boolean:      { name: "boolean" }
+        boolean:      { name: "boolean" },
+        json:         { name: "json" },
       }
 
       ##
@@ -134,6 +135,10 @@ module ActiveRecord
         true
       end
 
+      def supports_json?
+        true
+      end
+
       def supports_multi_insert?
         sqlite_version >= "3.7.11"
       end
@@ -369,6 +374,10 @@ module ActiveRecord
       end
 
       private
+        def initialize_type_map(m = type_map)
+          super
+          register_class_with_limit m, %r(int)i, SQLite3Integer
+        end
 
         def table_structure(table_name)
           structure = exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", "SCHEMA")
@@ -398,18 +407,21 @@ module ActiveRecord
           options[:id] = false
           create_table(to, options) do |definition|
             @definition = definition
-            @definition.primary_key(from_primary_key) if from_primary_key.present?
+            if from_primary_key.is_a?(Array)
+              @definition.primary_keys from_primary_key
+            end
             columns(from).each do |column|
               column_name = options[:rename] ?
                 (options[:rename][column.name] ||
                  options[:rename][column.name.to_sym] ||
                  column.name) : column.name
-              next if column_name == from_primary_key
 
               @definition.column(column_name, column.type,
                 limit: column.limit, default: column.default,
                 precision: column.precision, scale: column.scale,
-                null: column.null, collation: column.collation)
+                null: column.null, collation: column.collation,
+                primary_key: column_name == from_primary_key
+              )
             end
             yield @definition if block_given?
           end
@@ -422,6 +434,9 @@ module ActiveRecord
         def copy_table_indexes(from, to, rename = {})
           indexes(from).each do |index|
             name = index.name
+            # indexes sqlite creates for internal use start with `sqlite_` and
+            # don't need to be copied
+            next if name.starts_with?("sqlite_")
             if to == "a#{from}"
               name = "t#{name}"
             elsif from == "a#{to}"
@@ -524,6 +539,17 @@ module ActiveRecord
         def configure_connection
           execute("PRAGMA foreign_keys = ON", "SCHEMA")
         end
+
+        class SQLite3Integer < Type::Integer # :nodoc:
+          private
+            def _limit
+              # INTEGER storage class can be stored 8 bytes value.
+              # See https://www.sqlite.org/datatype3.html#storage_classes_and_datatypes
+              limit || 8
+            end
+        end
+
+        ActiveRecord::Type.register(:integer, SQLite3Integer, adapter: :sqlite3)
     end
     ActiveSupport.run_load_hooks(:active_record_sqlite3adapter, SQLite3Adapter)
   end
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 15e9c09ffb..5c10d4ff24 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -1045,7 +1045,7 @@ module ActiveRecord
         new(:up, migrations(migrations_paths), nil)
       end
 
-      def get_all_versions(connection = Base.connection)
+      def get_all_versions
         if SchemaMigration.table_exists?
           SchemaMigration.all_versions.map(&:to_i)
         else
@@ -1053,12 +1053,13 @@ module ActiveRecord
         end
       end
 
-      def current_version(connection = Base.connection)
-        get_all_versions(connection).max || 0
+      def current_version(connection = nil)
+        get_all_versions.max || 0
+      rescue ActiveRecord::NoDatabaseError
       end
 
-      def needs_migration?(connection = Base.connection)
-        (migrations(migrations_paths).collect(&:version) - get_all_versions(connection)).size > 0
+      def needs_migration?(connection = nil)
+        (migrations(migrations_paths).collect(&:version) - get_all_versions).size > 0
       end
 
       def any_migrations?
diff --git a/activerecord/lib/active_record/migration/compatibility.rb b/activerecord/lib/active_record/migration/compatibility.rb
index c979aaf0a0..bd8c054c28 100644
--- a/activerecord/lib/active_record/migration/compatibility.rb
+++ b/activerecord/lib/active_record/migration/compatibility.rb
@@ -16,6 +16,18 @@ module ActiveRecord
       V5_2 = Current
 
       class V5_1 < V5_2
+        def change_column(table_name, column_name, type, options = {})
+          if adapter_name == "PostgreSQL"
+            clear_cache!
+            sql = connection.send(:change_column_sql, table_name, column_name, type, options)
+            execute "ALTER TABLE #{quote_table_name(table_name)} #{sql}"
+            change_column_default(table_name, column_name, options[:default]) if options.key?(:default)
+            change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
+            change_column_comment(table_name, column_name, options[:comment]) if options.key?(:comment)
+          else
+            super
+          end
+        end
       end
 
       class V5_0 < V5_1
diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
index 4e1b05dbf6..a13b0d0181 100644
--- a/activerecord/lib/active_record/persistence.rb
+++ b/activerecord/lib/active_record/persistence.rb
@@ -99,7 +99,9 @@ module ActiveRecord
       # for updating all records in a single query.
       def update(id = :all, attributes)
         if id.is_a?(Array)
-          id.map.with_index { |one_id, idx| update(one_id, attributes[idx]) }.compact
+          id.map { |one_id| find(one_id) }.each_with_index { |object, idx|
+            object.update(attributes[idx])
+          }
         elsif id == :all
           all.each { |record| record.update(attributes) }
         else
@@ -112,7 +114,6 @@ module ActiveRecord
           object.update(attributes)
           object
         end
-      rescue RecordNotFound
       end
 
       # Destroy an object (or multiple objects) that has the given id. The object is instantiated first,
@@ -136,11 +137,10 @@ module ActiveRecord
       #   Todo.destroy(todos)
       def destroy(id)
         if id.is_a?(Array)
-          id.map { |one_id| destroy(one_id) }.compact
+          find(id).each(&:destroy)
         else
           find(id).destroy
         end
-      rescue RecordNotFound
       end
 
       # Deletes the row with a primary key matching the +id+ argument, using a
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 9ee8425e1b..4538ed6a5f 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -90,12 +90,15 @@ module ActiveRecord
             filename = File.join(app.config.paths["db"].first, "schema_cache.yml")
 
             if File.file?(filename)
+              current_version = ActiveRecord::Migrator.current_version
+              next if current_version.nil?
+
               cache = YAML.load(File.read(filename))
-              if cache.version == ActiveRecord::Migrator.current_version
+              if cache.version == current_version
                 connection.schema_cache = cache
                 connection_pool.schema_cache = cache.dup
               else
-                warn "Ignoring db/schema_cache.yml because it has expired. The current schema version is #{ActiveRecord::Migrator.current_version}, but the one in the cache is #{cache.version}."
+                warn "Ignoring db/schema_cache.yml because it has expired. The current schema version is #{current_version}, but the one in the cache is #{cache.version}."
               end
             end
           end
diff --git a/activerecord/lib/active_record/relation/where_clause.rb b/activerecord/lib/active_record/relation/where_clause.rb
index 752bb38481..a502713e56 100644
--- a/activerecord/lib/active_record/relation/where_clause.rb
+++ b/activerecord/lib/active_record/relation/where_clause.rb
@@ -47,7 +47,7 @@ module ActiveRecord
       end
 
       def to_h(table_name = nil)
-        equalities = predicates.grep(Arel::Nodes::Equality)
+        equalities = equalities(predicates)
         if table_name
           equalities = equalities.select do |node|
             node.left.relation.name == table_name
@@ -90,6 +90,20 @@ module ActiveRecord
         end
 
       private
+        def equalities(predicates)
+          equalities = []
+
+          predicates.each do |node|
+            case node
+            when Arel::Nodes::Equality
+              equalities << node
+            when Arel::Nodes::And
+              equalities.concat equalities(node.children)
+            end
+          end
+
+          equalities
+        end
 
         def predicates_unreferenced_by(other)
           predicates.reject do |n|
@@ -121,7 +135,7 @@ module ActiveRecord
         end
 
         def except_predicates(columns)
-          self.predicates.reject do |node|
+          predicates.reject do |node|
             case node
             when Arel::Nodes::Between, Arel::Nodes::In, Arel::Nodes::NotIn, Arel::Nodes::Equality, Arel::Nodes::NotEqual, Arel::Nodes::LessThan, Arel::Nodes::LessThanOrEqual, Arel::Nodes::GreaterThan, Arel::Nodes::GreaterThanOrEqual
               subrelation = (node.left.kind_of?(Arel::Attributes::Attribute) ? node.left : node.right)
diff --git a/activerecord/lib/active_record/schema_dumper.rb b/activerecord/lib/active_record/schema_dumper.rb
index 66f7d29886..16ccba6b6c 100644
--- a/activerecord/lib/active_record/schema_dumper.rb
+++ b/activerecord/lib/active_record/schema_dumper.rb
@@ -184,8 +184,9 @@ HEADER
           "name: #{index.name.inspect}",
         ]
         index_parts << "unique: true" if index.unique
-        index_parts << "length: { #{format_options(index.lengths)} }" if index.lengths.present?
-        index_parts << "order: { #{format_options(index.orders)} }" if index.orders.present?
+        index_parts << "length: #{format_index_parts(index.lengths)}" if index.lengths.present?
+        index_parts << "order: #{format_index_parts(index.orders)}" if index.orders.present?
+        index_parts << "opclass: #{format_index_parts(index.opclasses)}" if index.opclasses.present?
         index_parts << "where: #{index.where.inspect}" if index.where
         index_parts << "using: #{index.using.inspect}" if !@connection.default_index_type?(index)
         index_parts << "type: #{index.type.inspect}" if index.type
@@ -231,6 +232,14 @@ HEADER
         options.map { |key, value| "#{key}: #{value.inspect}" }.join(", ")
       end
 
+      def format_index_parts(options)
+        if options.is_a?(Hash)
+          "{ #{format_options(options)} }"
+        else
+          options.inspect
+        end
+      end
+
       def remove_prefix_and_suffix(table)
         prefix = Regexp.escape(@options[:table_name_prefix].to_s)
         suffix = Regexp.escape(@options[:table_name_suffix].to_s)
diff --git a/activerecord/test/cases/adapters/mysql2/connection_test.rb b/activerecord/test/cases/adapters/mysql2/connection_test.rb
index e61c70848a..13b4096671 100644
--- a/activerecord/test/cases/adapters/mysql2/connection_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/connection_test.rb
@@ -174,10 +174,10 @@ class Mysql2ConnectionTest < ActiveRecord::Mysql2TestCase
     assert_equal "SCHEMA", @subscriber.logged[0][1]
   end
 
-  def test_logs_name_rename_column_sql
+  def test_logs_name_rename_column_for_alter
     @connection.execute "CREATE TABLE `bar_baz` (`foo` varchar(255))"
     @subscriber.logged.clear
-    @connection.send(:rename_column_sql, "bar_baz", "foo", "foo2")
+    @connection.send(:rename_column_for_alter, "bar_baz", "foo", "foo2")
     assert_equal "SCHEMA", @subscriber.logged[0][1]
   ensure
     @connection.execute "DROP TABLE `bar_baz`"
diff --git a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
index 9929237546..99c53dadeb 100644
--- a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
@@ -59,6 +59,9 @@ class PostgresqlActiveSchemaTest < ActiveRecord::PostgreSQLTestCase
       assert_equal expected, add_index(:people, "lower(last_name)", using: type, unique: true)
     end
 
+    expected = %(CREATE  INDEX  "index_people_on_last_name" ON "people" USING gist ("last_name" bpchar_pattern_ops))
+    assert_equal expected, add_index(:people, :last_name, using: :gist, opclass: { last_name: :bpchar_pattern_ops })
+
     assert_raise ArgumentError do
       add_index(:people, :last_name, algorithm: :copy)
     end
diff --git a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
index f199519d86..1951230c8a 100644
--- a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
@@ -248,12 +248,12 @@ module ActiveRecord
 
       def test_index_with_opclass
         with_example_table do
-          @connection.add_index "ex", "data varchar_pattern_ops"
-          index = @connection.indexes("ex").find { |idx| idx.name == "index_ex_on_data_varchar_pattern_ops" }
-          assert_equal "data varchar_pattern_ops", index.columns
+          @connection.add_index "ex", "data", opclass: "varchar_pattern_ops"
+          index = @connection.indexes("ex").find { |idx| idx.name == "index_ex_on_data" }
+          assert_equal ["data"], index.columns
 
-          @connection.remove_index "ex", "data varchar_pattern_ops"
-          assert_not @connection.indexes("ex").find { |idx| idx.name == "index_ex_on_data_varchar_pattern_ops" }
+          @connection.remove_index "ex", "data"
+          assert_not @connection.indexes("ex").find { |idx| idx.name == "index_ex_on_data" }
         end
       end
 
diff --git a/activerecord/test/cases/adapters/postgresql/schema_test.rb b/activerecord/test/cases/adapters/postgresql/schema_test.rb
index 5a64da028b..1126908761 100644
--- a/activerecord/test/cases/adapters/postgresql/schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/schema_test.rb
@@ -459,7 +459,7 @@ class SchemaTest < ActiveRecord::PostgreSQLTestCase
         assert_equal :btree, index_d.using
         assert_equal :gin,   index_e.using
 
-        assert_equal :desc,  index_d.orders[INDEX_D_COLUMN]
+        assert_equal :desc,  index_d.orders
       end
     end
 
@@ -500,6 +500,38 @@ class SchemaForeignKeyTest < ActiveRecord::PostgreSQLTestCase
   end
 end
 
+class SchemaIndexOpclassTest < ActiveRecord::PostgreSQLTestCase
+  include SchemaDumpingHelper
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table "trains" do |t|
+      t.string :name
+      t.text :description
+    end
+  end
+
+  teardown do
+    @connection.drop_table "trains", if_exists: true
+  end
+
+  def test_string_opclass_is_dumped
+    @connection.execute "CREATE INDEX trains_name_and_description ON trains USING btree(name text_pattern_ops, description text_pattern_ops)"
+
+    output = dump_table_schema "trains"
+
+    assert_match(/opclass: :text_pattern_ops/, output)
+  end
+
+  def test_non_default_opclass_is_dumped
+    @connection.execute "CREATE INDEX trains_name_and_description ON trains USING btree(name, description text_pattern_ops)"
+
+    output = dump_table_schema "trains"
+
+    assert_match(/opclass: \{ description: :text_pattern_ops \}/, output)
+  end
+end
+
 class DefaultsUsingMultipleSchemasAndDomainTest < ActiveRecord::PostgreSQLTestCase
   setup do
     @connection = ActiveRecord::Base.connection
diff --git a/activerecord/test/cases/adapters/sqlite3/json_test.rb b/activerecord/test/cases/adapters/sqlite3/json_test.rb
index 568a524058..6f247fcd22 100644
--- a/activerecord/test/cases/adapters/sqlite3/json_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/json_test.rb
@@ -9,8 +9,8 @@ class SQLite3JSONTest < ActiveRecord::SQLite3TestCase
   def setup
     super
     @connection.create_table("json_data_type") do |t|
-      t.column "payload", :json, default: {}
-      t.column "settings", :json
+      t.json "payload", default: {}
+      t.json "settings"
     end
   end
 
diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
index 1f057fe5c6..1357719422 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
@@ -360,6 +360,51 @@ module ActiveRecord
         end
       end
 
+      class Barcode < ActiveRecord::Base
+        self.primary_key = "code"
+      end
+
+      def test_copy_table_with_existing_records_have_custom_primary_key
+        connection = Barcode.connection
+        connection.create_table(:barcodes, primary_key: "code", id: :string, limit: 42, force: true) do |t|
+          t.text :other_attr
+        end
+        code = "214fe0c2-dd47-46df-b53b-66090b3c1d40"
+        Barcode.create!(code: code, other_attr: "xxx")
+
+        connection.change_table "barcodes" do |t|
+          connection.remove_column("barcodes", "other_attr")
+        end
+
+        assert_equal code, Barcode.first.id
+      ensure
+        Barcode.reset_column_information
+      end
+
+      def test_copy_table_with_composite_primary_keys
+        connection = Barcode.connection
+        connection.create_table(:barcodes, primary_key: ["region", "code"], force: true) do |t|
+          t.string :region
+          t.string :code
+          t.text :other_attr
+        end
+        region = "US"
+        code = "214fe0c2-dd47-46df-b53b-66090b3c1d40"
+        Barcode.create!(region: region, code: code, other_attr: "xxx")
+
+        connection.change_table "barcodes" do |t|
+          connection.remove_column("barcodes", "other_attr")
+        end
+
+        assert_equal ["region", "code"], connection.primary_keys("barcodes")
+
+        barcode = Barcode.first
+        assert_equal region, barcode.region
+        assert_equal code, barcode.code
+      ensure
+        Barcode.reset_column_information
+      end
+
       def test_supports_extensions
         assert_not @conn.supports_extensions?, "does not support extensions"
       end
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index d79afa2ee9..3497f6aae4 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -891,11 +891,9 @@ class BasicsTest < ActiveRecord::TestCase
     assert_equal 2147483648, company.rating
   end
 
-  unless current_adapter?(:SQLite3Adapter)
-    def test_bignum_pk
-      company = Company.create!(id: 2147483648, name: "foo")
-      assert_equal company, Company.find(company.id)
-    end
+  def test_bignum_pk
+    company = Company.create!(id: 2147483648, name: "foo")
+    assert_equal company, Company.find(company.id)
   end
 
   # TODO: extend defaults tests to other databases!
diff --git a/activerecord/test/cases/json_attribute_test.rb b/activerecord/test/cases/json_attribute_test.rb
index 63f3c77fc3..afc39d0420 100644
--- a/activerecord/test/cases/json_attribute_test.rb
+++ b/activerecord/test/cases/json_attribute_test.rb
@@ -19,14 +19,14 @@ class JsonAttributeTest < ActiveRecord::TestCase
   def setup
     super
     @connection.create_table("json_data_type") do |t|
-      t.text "payload"
-      t.text "settings"
+      t.string "payload"
+      t.string "settings"
     end
   end
 
   private
     def column_type
-      :text
+      :string
     end
 
     def klass
diff --git a/activerecord/test/cases/json_shared_test_cases.rb b/activerecord/test/cases/json_shared_test_cases.rb
index a71485982c..b0c0f2c283 100644
--- a/activerecord/test/cases/json_shared_test_cases.rb
+++ b/activerecord/test/cases/json_shared_test_cases.rb
@@ -23,25 +23,23 @@ module JSONSharedTestCases
   def test_column
     column = klass.columns_hash["payload"]
     assert_equal column_type, column.type
-    assert_equal column_type.to_s, column.sql_type
+    assert_type_match column_type, column.sql_type
 
     type = klass.type_for_attribute("payload")
     assert_not type.binary?
   end
 
   def test_change_table_supports_json
-    skip unless @connection.supports_json?
     @connection.change_table("json_data_type") do |t|
       t.public_send column_type, "users"
     end
     klass.reset_column_information
     column = klass.columns_hash["users"]
     assert_equal column_type, column.type
-    assert_equal column_type.to_s, column.sql_type
+    assert_type_match column_type, column.sql_type
   end
 
   def test_schema_dumping
-    skip unless @connection.supports_json?
     output = dump_table_schema("json_data_type")
     assert_match(/t\.#{column_type}\s+"settings"/, output)
   end
@@ -68,26 +66,26 @@ module JSONSharedTestCases
   end
 
   def test_rewrite
-    @connection.execute(%q|insert into json_data_type (payload) VALUES ('{"k":"v"}')|)
+    @connection.execute(insert_statement_per_database('{"k":"v"}'))
     x = klass.first
     x.payload = { '"a\'' => "b" }
     assert x.save!
   end
 
   def test_select
-    @connection.execute(%q|insert into json_data_type (payload) VALUES ('{"k":"v"}')|)
+    @connection.execute(insert_statement_per_database('{"k":"v"}'))
     x = klass.first
     assert_equal({ "k" => "v" }, x.payload)
   end
 
   def test_select_multikey
-    @connection.execute(%q|insert into json_data_type (payload) VALUES ('{"k1":"v1", "k2":"v2", "k3":[1,2,3]}')|)
+    @connection.execute(insert_statement_per_database('{"k1":"v1", "k2":"v2", "k3":[1,2,3]}'))
     x = klass.first
     assert_equal({ "k1" => "v1", "k2" => "v2", "k3" => [1, 2, 3] }, x.payload)
   end
 
   def test_null_json
-    @connection.execute("insert into json_data_type (payload) VALUES(null)")
+    @connection.execute(insert_statement_per_database("null"))
     x = klass.first
     assert_nil(x.payload)
   end
@@ -109,13 +107,13 @@ module JSONSharedTestCases
   end
 
   def test_select_array_json_value
-    @connection.execute(%q|insert into json_data_type (payload) VALUES ('["v0",{"k1":"v1"}]')|)
+    @connection.execute(insert_statement_per_database('["v0",{"k1":"v1"}]'))
     x = klass.first
     assert_equal(["v0", { "k1" => "v1" }], x.payload)
   end
 
   def test_rewrite_array_json_value
-    @connection.execute(%q|insert into json_data_type (payload) VALUES ('["v0",{"k1":"v1"}]')|)
+    @connection.execute(insert_statement_per_database('["v0",{"k1":"v1"}]'))
     x = klass.first
     x.payload = ["v1", { "k2" => "v2" }, "v3"]
     assert x.save!
@@ -255,4 +253,17 @@ module JSONSharedTestCases
     def klass
       JsonDataType
     end
+
+    def assert_type_match(type, sql_type)
+      native_type = ActiveRecord::Base.connection.native_database_types[type][:name]
+      assert_match %r(\A#{native_type}\b), sql_type
+    end
+
+    def insert_statement_per_database(values)
+      if current_adapter?(:OracleAdapter)
+        "insert into json_data_type (id, payload) VALUES (json_data_type_seq.nextval, '#{values}')"
+      else
+        "insert into json_data_type (payload) VALUES ('#{values}')"
+      end
+    end
 end
diff --git a/activerecord/test/cases/migration/change_schema_test.rb b/activerecord/test/cases/migration/change_schema_test.rb
index 7b0644e9c0..38a906c8f5 100644
--- a/activerecord/test/cases/migration/change_schema_test.rb
+++ b/activerecord/test/cases/migration/change_schema_test.rb
@@ -264,19 +264,18 @@ module ActiveRecord
           t.column :foo, :timestamp
         end
 
-        klass = Class.new(ActiveRecord::Base)
-        klass.table_name = "testings"
+        column = connection.columns(:testings).find { |c| c.name == "foo" }
 
-        assert_equal :datetime, klass.columns_hash["foo"].type
+        assert_equal :datetime, column.type
 
         if current_adapter?(:PostgreSQLAdapter)
-          assert_equal "timestamp without time zone", klass.columns_hash["foo"].sql_type
+          assert_equal "timestamp without time zone", column.sql_type
         elsif current_adapter?(:Mysql2Adapter)
-          assert_equal "timestamp", klass.columns_hash["foo"].sql_type
+          assert_equal "timestamp", column.sql_type
         elsif current_adapter?(:OracleAdapter)
-          assert_equal "TIMESTAMP(6)", klass.columns_hash["foo"].sql_type
+          assert_equal "TIMESTAMP(6)", column.sql_type
         else
-          assert_equal klass.connection.type_to_sql("datetime"), klass.columns_hash["foo"].sql_type
+          assert_equal connection.type_to_sql("datetime"), column.sql_type
         end
       end
 
diff --git a/activerecord/test/cases/migration/compatibility_test.rb b/activerecord/test/cases/migration/compatibility_test.rb
index 2fef2f796e..cc2391f349 100644
--- a/activerecord/test/cases/migration/compatibility_test.rb
+++ b/activerecord/test/cases/migration/compatibility_test.rb
@@ -16,7 +16,7 @@ module ActiveRecord
         ActiveRecord::Migration.verbose = false
 
         connection.create_table :testings do |t|
-          t.column :foo, :string, limit: 100
+          t.column :foo, :string, limit: 5
           t.column :bar, :string, limit: 100
         end
       end
@@ -126,6 +126,25 @@ module ActiveRecord
         end
         assert_match(/LegacyMigration < ActiveRecord::Migration\[4\.2\]/, e.message)
       end
+
+      if current_adapter?(:PostgreSQLAdapter)
+        class Testing < ActiveRecord::Base
+        end
+
+        def test_legacy_change_column_with_null_executes_update
+          migration = Class.new(ActiveRecord::Migration[5.1]) {
+            def migrate(x)
+              change_column :testings, :foo, :string, limit: 10, null: false, default: "foobar"
+            end
+          }.new
+
+          Testing.create!
+          ActiveRecord::Migrator.new(:up, [migration]).migrate
+          assert_equal ["foobar"], Testing.all.map(&:foo)
+        ensure
+          ActiveRecord::Base.clear_cache!
+        end
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/migration/foreign_key_test.rb b/activerecord/test/cases/migration/foreign_key_test.rb
index 499d072de5..079be04946 100644
--- a/activerecord/test/cases/migration/foreign_key_test.rb
+++ b/activerecord/test/cases/migration/foreign_key_test.rb
@@ -227,6 +227,74 @@ if ActiveRecord::Base.connection.supports_foreign_keys?
           end
         end
 
+        if ActiveRecord::Base.connection.supports_validate_constraints?
+          def test_add_invalid_foreign_key
+            @connection.add_foreign_key :astronauts, :rockets, column: "rocket_id", validate: false
+
+            foreign_keys = @connection.foreign_keys("astronauts")
+            assert_equal 1, foreign_keys.size
+
+            fk = foreign_keys.first
+            refute fk.validated?
+          end
+
+          def test_validate_foreign_key_infers_column
+            @connection.add_foreign_key :astronauts, :rockets, validate: false
+            refute @connection.foreign_keys("astronauts").first.validated?
+
+            @connection.validate_foreign_key :astronauts, :rockets
+            assert @connection.foreign_keys("astronauts").first.validated?
+          end
+
+          def test_validate_foreign_key_by_column
+            @connection.add_foreign_key :astronauts, :rockets, column: "rocket_id", validate: false
+            refute @connection.foreign_keys("astronauts").first.validated?
+
+            @connection.validate_foreign_key :astronauts, column: "rocket_id"
+            assert @connection.foreign_keys("astronauts").first.validated?
+          end
+
+          def test_validate_foreign_key_by_symbol_column
+            @connection.add_foreign_key :astronauts, :rockets, column: :rocket_id, validate: false
+            refute @connection.foreign_keys("astronauts").first.validated?
+
+            @connection.validate_foreign_key :astronauts, column: :rocket_id
+            assert @connection.foreign_keys("astronauts").first.validated?
+          end
+
+          def test_validate_foreign_key_by_name
+            @connection.add_foreign_key :astronauts, :rockets, column: "rocket_id", name: "fancy_named_fk", validate: false
+            refute @connection.foreign_keys("astronauts").first.validated?
+
+            @connection.validate_foreign_key :astronauts, name: "fancy_named_fk"
+            assert @connection.foreign_keys("astronauts").first.validated?
+          end
+
+          def test_validate_foreign_non_existing_foreign_key_raises
+            assert_raises ArgumentError do
+              @connection.validate_foreign_key :astronauts, :rockets
+            end
+          end
+
+          def test_validate_constraint_by_name
+            @connection.add_foreign_key :astronauts, :rockets, column: "rocket_id", name: "fancy_named_fk", validate: false
+
+            @connection.validate_constraint :astronauts, "fancy_named_fk"
+            assert @connection.foreign_keys("astronauts").first.validated?
+          end
+        else
+          # Foreign key should still be created, but should not be invalid
+          def test_add_invalid_foreign_key
+            @connection.add_foreign_key :astronauts, :rockets, column: "rocket_id", validate: false
+
+            foreign_keys = @connection.foreign_keys("astronauts")
+            assert_equal 1, foreign_keys.size
+
+            fk = foreign_keys.first
+            assert fk.validated?
+          end
+        end
+
         def test_schema_dumping
           @connection.add_foreign_key :astronauts, :rockets
           output = dump_table_schema "astronauts"
diff --git a/activerecord/test/cases/persistence_test.rb b/activerecord/test/cases/persistence_test.rb
index f088c064f5..4cc66a2e49 100644
--- a/activerecord/test/cases/persistence_test.rb
+++ b/activerecord/test/cases/persistence_test.rb
@@ -70,7 +70,7 @@ class PersistenceTest < ActiveRecord::TestCase
   end
 
   def test_update_many
-    topic_data = { 1 => { "content" => "1 updated" }, 2 => { "content" => "2 updated" }, nil => {} }
+    topic_data = { 1 => { "content" => "1 updated" }, 2 => { "content" => "2 updated" } }
     updated = Topic.update(topic_data.keys, topic_data.values)
 
     assert_equal [1, 2], updated.map(&:id)
@@ -78,10 +78,33 @@ class PersistenceTest < ActiveRecord::TestCase
     assert_equal "2 updated", Topic.find(2).content
   end
 
+  def test_update_many_with_duplicated_ids
+    updated = Topic.update([1, 1, 2], [
+      { "content" => "1 duplicated" }, { "content" => "1 updated" }, { "content" => "2 updated" }
+    ])
+
+    assert_equal [1, 1, 2], updated.map(&:id)
+    assert_equal "1 updated", Topic.find(1).content
+    assert_equal "2 updated", Topic.find(2).content
+  end
+
+  def test_update_many_with_invalid_id
+    topic_data = { 1 => { "content" => "1 updated" }, 2 => { "content" => "2 updated" }, 99999 => {} }
+
+    assert_raise(ActiveRecord::RecordNotFound) do
+      Topic.update(topic_data.keys, topic_data.values)
+    end
+
+    assert_not_equal "1 updated", Topic.find(1).content
+    assert_not_equal "2 updated", Topic.find(2).content
+  end
+
   def test_class_level_update_is_affected_by_scoping
     topic_data = { 1 => { "content" => "1 updated" }, 2 => { "content" => "2 updated" } }
 
-    assert_equal [], Topic.where("1=0").scoping { Topic.update(topic_data.keys, topic_data.values) }
+    assert_raise(ActiveRecord::RecordNotFound) do
+      Topic.where("1=0").scoping { Topic.update(topic_data.keys, topic_data.values) }
+    end
 
     assert_not_equal "1 updated", Topic.find(1).content
     assert_not_equal "2 updated", Topic.find(2).content
@@ -175,15 +198,25 @@ class PersistenceTest < ActiveRecord::TestCase
   end
 
   def test_destroy_many
-    clients = Client.all.merge!(order: "id").find([2, 3])
+    clients = Client.find([2, 3])
 
     assert_difference("Client.count", -2) do
-      destroyed = Client.destroy([2, 3, nil]).sort_by(&:id)
+      destroyed = Client.destroy([2, 3])
       assert_equal clients, destroyed
       assert destroyed.all?(&:frozen?), "destroyed clients should be frozen"
     end
   end
 
+  def test_destroy_many_with_invalid_id
+    clients = Client.find([2, 3])
+
+    assert_raise(ActiveRecord::RecordNotFound) do
+      Client.destroy([2, 3, 99999])
+    end
+
+    assert_equal clients, Client.find([2, 3])
+  end
+
   def test_becomes
     assert_kind_of Reply, topics(:first).becomes(Reply)
     assert_equal "The First Topic", topics(:first).becomes(Reply).title
@@ -473,10 +506,18 @@ class PersistenceTest < ActiveRecord::TestCase
     assert_raise(ActiveRecord::RecordNotFound) { Topic.find(topic.id) }
   end
 
-  def test_record_not_found_exception
+  def test_find_raises_record_not_found_exception
     assert_raise(ActiveRecord::RecordNotFound) { Topic.find(99999) }
   end
 
+  def test_update_raises_record_not_found_exception
+    assert_raise(ActiveRecord::RecordNotFound) { Topic.update(99999, approved: true) }
+  end
+
+  def test_destroy_raises_record_not_found_exception
+    assert_raise(ActiveRecord::RecordNotFound) { Topic.destroy(99999) }
+  end
+
   def test_update_all
     assert_equal Topic.count, Topic.update_all("content = 'bulk updated!'")
     assert_equal "bulk updated!", Topic.find(1).content
@@ -938,7 +979,9 @@ class PersistenceTest < ActiveRecord::TestCase
     should_not_be_destroyed_reply = Reply.create("title" => "hello", "content" => "world")
     Topic.find(1).replies << should_not_be_destroyed_reply
 
-    assert_nil Topic.where("1=0").scoping { Topic.destroy(1) }
+    assert_raise(ActiveRecord::RecordNotFound) do
+      Topic.where("1=0").scoping { Topic.destroy(1) }
+    end
 
     assert_nothing_raised { Topic.find(1) }
     assert_nothing_raised { Reply.find(should_not_be_destroyed_reply.id) }
diff --git a/activerecord/test/cases/relation_test.rb b/activerecord/test/cases/relation_test.rb
index a71d8de521..b424ca91de 100644
--- a/activerecord/test/cases/relation_test.rb
+++ b/activerecord/test/cases/relation_test.rb
@@ -68,7 +68,7 @@ module ActiveRecord
       relation = Relation.new(Post, Post.arel_table, Post.predicate_builder)
       left     = relation.table[:id].eq(10)
       right    = relation.table[:id].eq(10)
-      combine  = left.and right
+      combine  = left.or(right)
       relation.where! combine
       assert_equal({}, relation.where_values_hash)
     end
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 50ad1d5b26..675aafabda 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1189,6 +1189,15 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal "hen", hen.name
   end
 
+  def test_create_with_polymorphic_association
+    author = authors(:david)
+    post = posts(:welcome)
+    comment = Comment.where(post: post, author: author).create!(body: "hello")
+
+    assert_equal author, comment.author
+    assert_equal post, comment.post
+  end
+
   def test_first_or_create
     parrot = Bird.where(color: "green").first_or_create(name: "parrot")
     assert_kind_of Bird, parrot
diff --git a/activerecord/test/cases/schema_dumper_test.rb b/activerecord/test/cases/schema_dumper_test.rb
index ac5092f1c1..a612ce9bb2 100644
--- a/activerecord/test/cases/schema_dumper_test.rb
+++ b/activerecord/test/cases/schema_dumper_test.rb
@@ -177,14 +177,14 @@ class SchemaDumperTest < ActiveRecord::TestCase
 
   def test_schema_dumps_index_columns_in_right_order
     index_definition = dump_table_schema("companies").split(/\n/).grep(/t\.index.*company_index/).first.strip
-    if current_adapter?(:PostgreSQLAdapter, :SQLite3Adapter)
-      assert_equal 't.index ["firm_id", "type", "rating"], name: "company_index", order: { rating: :desc }', index_definition
-    elsif current_adapter?(:Mysql2Adapter)
+    if current_adapter?(:Mysql2Adapter)
       if ActiveRecord::Base.connection.supports_index_sort_order?
         assert_equal 't.index ["firm_id", "type", "rating"], name: "company_index", length: { type: 10 }, order: { rating: :desc }', index_definition
       else
         assert_equal 't.index ["firm_id", "type", "rating"], name: "company_index", length: { type: 10 }', index_definition
       end
+    elsif ActiveRecord::Base.connection.supports_index_sort_order?
+      assert_equal 't.index ["firm_id", "type", "rating"], name: "company_index", order: { rating: :desc }', index_definition
     else
       assert_equal 't.index ["firm_id", "type", "rating"], name: "company_index"', index_definition
     end
@@ -199,6 +199,24 @@ class SchemaDumperTest < ActiveRecord::TestCase
     end
   end
 
+  def test_schema_dumps_index_sort_order
+    index_definition = dump_table_schema("companies").split(/\n/).grep(/t\.index.*_name_and_rating/).first.strip
+    if ActiveRecord::Base.connection.supports_index_sort_order?
+      assert_equal 't.index ["name", "rating"], name: "index_companies_on_name_and_rating", order: :desc', index_definition
+    else
+      assert_equal 't.index ["name", "rating"], name: "index_companies_on_name_and_rating"', index_definition
+    end
+  end
+
+  def test_schema_dumps_index_length
+    index_definition = dump_table_schema("companies").split(/\n/).grep(/t\.index.*_name_and_description/).first.strip
+    if current_adapter?(:Mysql2Adapter)
+      assert_equal 't.index ["name", "description"], name: "index_companies_on_name_and_description", length: 10', index_definition
+    else
+      assert_equal 't.index ["name", "description"], name: "index_companies_on_name_and_description"', index_definition
+    end
+  end
+
   def test_schema_dump_should_honor_nonstandard_primary_keys
     output = standard_dump
     match = output.match(%r{create_table "movies"(.*)do})
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index a4505a4892..bf66846840 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -205,6 +205,8 @@ ActiveRecord::Schema.define do
     t.bigint :rating, default: 1
     t.integer :account_id
     t.string :description, default: ""
+    t.index [:name, :rating], order: :desc
+    t.index [:name, :description], length: 10
     t.index [:firm_id, :type, :rating], name: "company_index", length: { type: 10 }, order: { rating: :desc }
     t.index [:firm_id, :type], name: "company_partial_index", where: "(rating > 10)"
     t.index :name, name: "company_name_index", using: :btree
diff --git a/activestorage/app/models/active_storage/blob.rb b/activestorage/app/models/active_storage/blob.rb
index 2aa05d665e..acaf22fac1 100644
--- a/activestorage/app/models/active_storage/blob.rb
+++ b/activestorage/app/models/active_storage/blob.rb
@@ -270,7 +270,8 @@ class ActiveStorage::Blob < ActiveRecord::Base
   # deleted as well or you will essentially have a dead reference. It's recommended to use the +#purge+ and +#purge_later+
   # methods in most circumstances.
   def delete
-    service.delete key
+    service.delete(key)
+    service.delete_prefixed("variants/#{key}/") if image?
   end
 
   # Deletes the file on the service and then destroys the blob record. This is the recommended way to dispose of unwanted
diff --git a/activestorage/lib/active_storage/analyzer/video_analyzer.rb b/activestorage/lib/active_storage/analyzer/video_analyzer.rb
index 408b5e58e9..1c144baa37 100644
--- a/activestorage/lib/active_storage/analyzer/video_analyzer.rb
+++ b/activestorage/lib/active_storage/analyzer/video_analyzer.rb
@@ -19,6 +19,8 @@ module ActiveStorage
   # This analyzer requires the {ffmpeg}[https://www.ffmpeg.org] system library, which is not provided by Rails. You must
   # install ffmpeg yourself to use this analyzer.
   class Analyzer::VideoAnalyzer < Analyzer
+    class_attribute :ffprobe_path, default: "ffprobe"
+
     def self.accept?(blob)
       blob.video?
     end
@@ -29,10 +31,18 @@ module ActiveStorage
 
     private
       def width
-        Integer(video_stream["width"]) if video_stream["width"]
+        rotated? ? raw_height : raw_width
       end
 
       def height
+        rotated? ? raw_width : raw_height
+      end
+
+      def raw_width
+        Integer(video_stream["width"]) if video_stream["width"]
+      end
+
+      def raw_height
         Integer(video_stream["height"]) if video_stream["height"]
       end
 
@@ -50,6 +60,10 @@ module ActiveStorage
         end
       end
 
+      def rotated?
+        angle == 90 || angle == 270
+      end
+
 
       def tags
         @tags ||= video_stream["tags"] || {}
@@ -68,7 +82,7 @@ module ActiveStorage
       end
 
       def probe_from(file)
-        IO.popen([ "ffprobe", "-print_format", "json", "-show_streams", "-v", "error", file.path ]) do |output|
+        IO.popen([ ffprobe_path, "-print_format", "json", "-show_streams", "-v", "error", file.path ]) do |output|
           JSON.parse(output.read)
         end
       rescue Errno::ENOENT
diff --git a/activestorage/lib/active_storage/engine.rb b/activestorage/lib/active_storage/engine.rb
index 6cf6635c4f..b870e6d4d6 100644
--- a/activestorage/lib/active_storage/engine.rb
+++ b/activestorage/lib/active_storage/engine.rb
@@ -15,7 +15,8 @@ module ActiveStorage
 
     config.active_storage = ActiveSupport::OrderedOptions.new
     config.active_storage.previewers = [ ActiveStorage::Previewer::PDFPreviewer, ActiveStorage::Previewer::VideoPreviewer ]
-    config.active_storage.analyzers  = [ ActiveStorage::Analyzer::ImageAnalyzer, ActiveStorage::Analyzer::VideoAnalyzer ]
+    config.active_storage.analyzers = [ ActiveStorage::Analyzer::ImageAnalyzer, ActiveStorage::Analyzer::VideoAnalyzer ]
+    config.active_storage.paths = ActiveSupport::OrderedOptions.new
 
     config.eager_load_namespaces << ActiveStorage
 
@@ -68,5 +69,21 @@ module ActiveStorage
         end
       end
     end
+
+    initializer "active_storage.paths" do
+      config.after_initialize do |app|
+        if ffprobe_path = app.config.active_storage.paths.ffprobe
+          ActiveStorage::Analyzer::VideoAnalyzer.ffprobe_path = ffprobe_path
+        end
+
+        if ffmpeg_path = app.config.active_storage.paths.ffmpeg
+          ActiveStorage::Previewer::VideoPreviewer.ffmpeg_path = ffmpeg_path
+        end
+
+        if mutool_path = app.config.active_storage.paths.mutool
+          ActiveStorage::Previewer::PDFPreviewer.mutool_path = mutool_path
+        end
+      end
+    end
   end
 end
diff --git a/activestorage/lib/active_storage/log_subscriber.rb b/activestorage/lib/active_storage/log_subscriber.rb
index 5cbf4bd1a5..a4e148c1a5 100644
--- a/activestorage/lib/active_storage/log_subscriber.rb
+++ b/activestorage/lib/active_storage/log_subscriber.rb
@@ -18,6 +18,10 @@ module ActiveStorage
       info event, color("Deleted file from key: #{key_in(event)}", RED)
     end
 
+    def service_delete_prefixed(event)
+      info event, color("Deleted files by key prefix: #{event.payload[:prefix]}", RED)
+    end
+
     def service_exist(event)
       debug event, color("Checked if file exists at key: #{key_in(event)} (#{event.payload[:exist] ? "yes" : "no"})", BLUE)
     end
diff --git a/activestorage/lib/active_storage/previewer.rb b/activestorage/lib/active_storage/previewer.rb
index ed75bae3b5..3d485988e9 100644
--- a/activestorage/lib/active_storage/previewer.rb
+++ b/activestorage/lib/active_storage/previewer.rb
@@ -54,5 +54,9 @@ module ActiveStorage
         IO.popen(argv) { |out| IO.copy_stream(out, to) }
         to.rewind
       end
+
+      def logger
+        ActiveStorage.logger
+      end
   end
 end
diff --git a/activestorage/lib/active_storage/previewer/pdf_previewer.rb b/activestorage/lib/active_storage/previewer/pdf_previewer.rb
index a2f05c74a6..b84aefcc9c 100644
--- a/activestorage/lib/active_storage/previewer/pdf_previewer.rb
+++ b/activestorage/lib/active_storage/previewer/pdf_previewer.rb
@@ -2,16 +2,23 @@
 
 module ActiveStorage
   class Previewer::PDFPreviewer < Previewer
+    class_attribute :mutool_path, default: "mutool"
+
     def self.accept?(blob)
       blob.content_type == "application/pdf"
     end
 
     def preview
       download_blob_to_tempfile do |input|
-        draw "mutool", "draw", "-F", "png", "-o", "-", input.path, "1" do |output|
+        draw_first_page_from input do |output|
           yield io: output, filename: "#{blob.filename.base}.png", content_type: "image/png"
         end
       end
     end
+
+    private
+      def draw_first_page_from(file, &block)
+        draw mutool_path, "draw", "-F", "png", "-o", "-", file.path, "1", &block
+      end
   end
 end
diff --git a/activestorage/lib/active_storage/previewer/video_previewer.rb b/activestorage/lib/active_storage/previewer/video_previewer.rb
index 49f128d142..5d06e33f44 100644
--- a/activestorage/lib/active_storage/previewer/video_previewer.rb
+++ b/activestorage/lib/active_storage/previewer/video_previewer.rb
@@ -2,6 +2,8 @@
 
 module ActiveStorage
   class Previewer::VideoPreviewer < Previewer
+    class_attribute :ffmpeg_path, default: "ffmpeg"
+
     def self.accept?(blob)
       blob.video?
     end
@@ -16,7 +18,7 @@ module ActiveStorage
 
     private
       def draw_relevant_frame_from(file, &block)
-        draw "ffmpeg", "-i", file.path, "-y", "-vcodec", "png",
+        draw ffmpeg_path, "-i", file.path, "-y", "-vcodec", "png",
           "-vf", "thumbnail", "-vframes", "1", "-f", "image2", "-", &block
       end
   end
diff --git a/activestorage/lib/active_storage/service.rb b/activestorage/lib/active_storage/service.rb
index 343e5587d5..f2e1269f27 100644
--- a/activestorage/lib/active_storage/service.rb
+++ b/activestorage/lib/active_storage/service.rb
@@ -78,6 +78,11 @@ module ActiveStorage
       raise NotImplementedError
     end
 
+    # Delete files at keys starting with the +prefix+.
+    def delete_prefixed(prefix)
+      raise NotImplementedError
+    end
+
     # Return +true+ if a file exists at the +key+.
     def exist?(key)
       raise NotImplementedError
@@ -104,10 +109,10 @@ module ActiveStorage
     end
 
     private
-      def instrument(operation, key, payload = {}, &block)
+      def instrument(operation, payload = {}, &block)
         ActiveSupport::Notifications.instrument(
           "service_#{operation}.active_storage",
-          payload.merge(key: key, service: service_name), &block)
+          payload.merge(service: service_name), &block)
       end
 
       def service_name
diff --git a/activestorage/lib/active_storage/service/azure_storage_service.rb b/activestorage/lib/active_storage/service/azure_storage_service.rb
index f3877ad9c9..19b09991b3 100644
--- a/activestorage/lib/active_storage/service/azure_storage_service.rb
+++ b/activestorage/lib/active_storage/service/azure_storage_service.rb
@@ -19,7 +19,7 @@ module ActiveStorage
     end
 
     def upload(key, io, checksum: nil)
-      instrument :upload, key, checksum: checksum do
+      instrument :upload, key: key, checksum: checksum do
         begin
           blobs.create_block_blob(container, key, io, content_md5: checksum)
         rescue Azure::Core::Http::HTTPError
@@ -30,11 +30,11 @@ module ActiveStorage
 
     def download(key, &block)
       if block_given?
-        instrument :streaming_download, key do
+        instrument :streaming_download, key: key do
           stream(key, &block)
         end
       else
-        instrument :download, key do
+        instrument :download, key: key do
           _, io = blobs.get_blob(container, key)
           io.force_encoding(Encoding::BINARY)
         end
@@ -42,7 +42,7 @@ module ActiveStorage
     end
 
     def delete(key)
-      instrument :delete, key do
+      instrument :delete, key: key do
         begin
           blobs.delete_blob(container, key)
         rescue Azure::Core::Http::HTTPError
@@ -51,8 +51,24 @@ module ActiveStorage
       end
     end
 
+    def delete_prefixed(prefix)
+      instrument :delete_prefixed, prefix: prefix do
+        marker = nil
+
+        loop do
+          results = blobs.list_blobs(container, prefix: prefix, marker: marker)
+
+          results.each do |blob|
+            blobs.delete_blob(container, blob.name)
+          end
+
+          break unless marker = results.continuation_token.presence
+        end
+      end
+    end
+
     def exist?(key)
-      instrument :exist, key do |payload|
+      instrument :exist, key: key do |payload|
         answer = blob_for(key).present?
         payload[:exist] = answer
         answer
@@ -60,7 +76,7 @@ module ActiveStorage
     end
 
     def url(key, expires_in:, filename:, disposition:, content_type:)
-      instrument :url, key do |payload|
+      instrument :url, key: key do |payload|
         base_url = url_for(key)
         generated_url = signer.signed_uri(
           URI(base_url), false,
@@ -77,7 +93,7 @@ module ActiveStorage
     end
 
     def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
-      instrument :url, key do |payload|
+      instrument :url, key: key do |payload|
         base_url = url_for(key)
         generated_url = signer.signed_uri(URI(base_url), false, permissions: "rw",
           expiry: format_expiry(expires_in)).to_s
diff --git a/activestorage/lib/active_storage/service/disk_service.rb b/activestorage/lib/active_storage/service/disk_service.rb
index 52eaba4e7b..a8728c5bc3 100644
--- a/activestorage/lib/active_storage/service/disk_service.rb
+++ b/activestorage/lib/active_storage/service/disk_service.rb
@@ -16,7 +16,7 @@ module ActiveStorage
     end
 
     def upload(key, io, checksum: nil)
-      instrument :upload, key, checksum: checksum do
+      instrument :upload, key: key, checksum: checksum do
         IO.copy_stream(io, make_path_for(key))
         ensure_integrity_of(key, checksum) if checksum
       end
@@ -24,7 +24,7 @@ module ActiveStorage
 
     def download(key)
       if block_given?
-        instrument :streaming_download, key do
+        instrument :streaming_download, key: key do
           File.open(path_for(key), "rb") do |file|
             while data = file.read(64.kilobytes)
               yield data
@@ -32,14 +32,14 @@ module ActiveStorage
           end
         end
       else
-        instrument :download, key do
+        instrument :download, key: key do
           File.binread path_for(key)
         end
       end
     end
 
     def delete(key)
-      instrument :delete, key do
+      instrument :delete, key: key do
         begin
           File.delete path_for(key)
         rescue Errno::ENOENT
@@ -48,8 +48,16 @@ module ActiveStorage
       end
     end
 
+    def delete_prefixed(prefix)
+      instrument :delete_prefixed, prefix: prefix do
+        Dir.glob(path_for("#{prefix}*")).each do |path|
+          FileUtils.rm_rf(path)
+        end
+      end
+    end
+
     def exist?(key)
-      instrument :exist, key do |payload|
+      instrument :exist, key: key do |payload|
         answer = File.exist? path_for(key)
         payload[:exist] = answer
         answer
@@ -57,7 +65,7 @@ module ActiveStorage
     end
 
     def url(key, expires_in:, filename:, disposition:, content_type:)
-      instrument :url, key do |payload|
+      instrument :url, key: key do |payload|
         verified_key_with_expiration = ActiveStorage.verifier.generate(key, expires_in: expires_in, purpose: :blob_key)
 
         generated_url =
@@ -77,7 +85,7 @@ module ActiveStorage
     end
 
     def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
-      instrument :url, key do |payload|
+      instrument :url, key: key do |payload|
         verified_token_with_expiration = ActiveStorage.verifier.generate(
           {
             key: key,
diff --git a/activestorage/lib/active_storage/service/gcs_service.rb b/activestorage/lib/active_storage/service/gcs_service.rb
index fd9916634a..6f6f4105fe 100644
--- a/activestorage/lib/active_storage/service/gcs_service.rb
+++ b/activestorage/lib/active_storage/service/gcs_service.rb
@@ -14,9 +14,15 @@ module ActiveStorage
     end
 
     def upload(key, io, checksum: nil)
-      instrument :upload, key, checksum: checksum do
+      instrument :upload, key: key, checksum: checksum do
         begin
-          bucket.create_file(io, key, md5: checksum)
+          # The official GCS client library doesn't allow us to create a file with no Content-Type metadata.
+          # We need the file we create to have no Content-Type so we can control it via the response-content-type
+          # param in signed URLs. Workaround: let the GCS client create the file with an inferred
+          # Content-Type (usually "application/octet-stream") then clear it.
+          bucket.create_file(io, key, md5: checksum).update do |file|
+            file.content_type = nil
+          end
         rescue Google::Cloud::InvalidArgumentError
           raise ActiveStorage::IntegrityError
         end
@@ -25,7 +31,7 @@ module ActiveStorage
 
     # FIXME: Download in chunks when given a block.
     def download(key)
-      instrument :download, key do
+      instrument :download, key: key do
         io = file_for(key).download
         io.rewind
 
@@ -38,7 +44,7 @@ module ActiveStorage
     end
 
     def delete(key)
-      instrument :delete, key do
+      instrument :delete, key: key do
         begin
           file_for(key).delete
         rescue Google::Cloud::NotFoundError
@@ -47,8 +53,14 @@ module ActiveStorage
       end
     end
 
+    def delete_prefixed(prefix)
+      instrument :delete_prefixed, prefix: prefix do
+        bucket.files(prefix: prefix).all(&:delete)
+      end
+    end
+
     def exist?(key)
-      instrument :exist, key do |payload|
+      instrument :exist, key: key do |payload|
         answer = file_for(key).exists?
         payload[:exist] = answer
         answer
@@ -56,7 +68,7 @@ module ActiveStorage
     end
 
     def url(key, expires_in:, filename:, content_type:, disposition:)
-      instrument :url, key do |payload|
+      instrument :url, key: key do |payload|
         generated_url = file_for(key).signed_url expires: expires_in, query: {
           "response-content-disposition" => content_disposition_with(type: disposition, filename: filename),
           "response-content-type" => content_type
@@ -69,7 +81,7 @@ module ActiveStorage
     end
 
     def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
-      instrument :url, key do |payload|
+      instrument :url, key: key do |payload|
         generated_url = bucket.signed_url key, method: "PUT", expires: expires_in,
           content_type: content_type, content_md5: checksum
 
diff --git a/activestorage/lib/active_storage/service/mirror_service.rb b/activestorage/lib/active_storage/service/mirror_service.rb
index 39e922f7ab..7eca8ce7f4 100644
--- a/activestorage/lib/active_storage/service/mirror_service.rb
+++ b/activestorage/lib/active_storage/service/mirror_service.rb
@@ -35,6 +35,11 @@ module ActiveStorage
       perform_across_services :delete, key
     end
 
+    # Delete files at keys starting with the +prefix+ on all services.
+    def delete_prefixed(prefix)
+      perform_across_services :delete_prefixed, prefix
+    end
+
     private
       def each_service(&block)
         [ primary, *mirrors ].each(&block)
diff --git a/activestorage/lib/active_storage/service/s3_service.rb b/activestorage/lib/active_storage/service/s3_service.rb
index 6957119780..c95672f338 100644
--- a/activestorage/lib/active_storage/service/s3_service.rb
+++ b/activestorage/lib/active_storage/service/s3_service.rb
@@ -17,7 +17,7 @@ module ActiveStorage
     end
 
     def upload(key, io, checksum: nil)
-      instrument :upload, key, checksum: checksum do
+      instrument :upload, key: key, checksum: checksum do
         begin
           object_for(key).put(upload_options.merge(body: io, content_md5: checksum))
         rescue Aws::S3::Errors::BadDigest
@@ -28,24 +28,30 @@ module ActiveStorage
 
     def download(key, &block)
       if block_given?
-        instrument :streaming_download, key do
+        instrument :streaming_download, key: key do
           stream(key, &block)
         end
       else
-        instrument :download, key do
+        instrument :download, key: key do
           object_for(key).get.body.read.force_encoding(Encoding::BINARY)
         end
       end
     end
 
     def delete(key)
-      instrument :delete, key do
+      instrument :delete, key: key do
         object_for(key).delete
       end
     end
 
+    def delete_prefixed(prefix)
+      instrument :delete_prefixed, prefix: prefix do
+        bucket.objects(prefix: prefix).batch_delete!
+      end
+    end
+
     def exist?(key)
-      instrument :exist, key do |payload|
+      instrument :exist, key: key do |payload|
         answer = object_for(key).exists?
         payload[:exist] = answer
         answer
@@ -53,7 +59,7 @@ module ActiveStorage
     end
 
     def url(key, expires_in:, filename:, disposition:, content_type:)
-      instrument :url, key do |payload|
+      instrument :url, key: key do |payload|
         generated_url = object_for(key).presigned_url :get, expires_in: expires_in.to_i,
           response_content_disposition: content_disposition_with(type: disposition, filename: filename),
           response_content_type: content_type
@@ -65,7 +71,7 @@ module ActiveStorage
     end
 
     def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
-      instrument :url, key do |payload|
+      instrument :url, key: key do |payload|
         generated_url = object_for(key).presigned_url :put, expires_in: expires_in.to_i,
           content_type: content_type, content_length: content_length, content_md5: checksum
 
diff --git a/activestorage/test/analyzer/video_analyzer_test.rb b/activestorage/test/analyzer/video_analyzer_test.rb
index 4a3c4a8bfc..b3b9c97fe4 100644
--- a/activestorage/test/analyzer/video_analyzer_test.rb
+++ b/activestorage/test/analyzer/video_analyzer_test.rb
@@ -21,8 +21,8 @@ class ActiveStorage::Analyzer::VideoAnalyzerTest < ActiveSupport::TestCase
     blob = create_file_blob(filename: "rotated_video.mp4", content_type: "video/mp4")
     metadata = blob.tap(&:analyze).metadata
 
-    assert_equal 640, metadata[:width]
-    assert_equal 480, metadata[:height]
+    assert_equal 480, metadata[:width]
+    assert_equal 640, metadata[:height]
     assert_equal [4, 3], metadata[:aspect_ratio]
     assert_equal 5.227975, metadata[:duration]
     assert_equal 90, metadata[:angle]
diff --git a/activestorage/test/models/blob_test.rb b/activestorage/test/models/blob_test.rb
index 6e815997ba..f94e65ed77 100644
--- a/activestorage/test/models/blob_test.rb
+++ b/activestorage/test/models/blob_test.rb
@@ -41,13 +41,21 @@ class ActiveStorage::BlobTest < ActiveSupport::TestCase
     end
   end
 
-  test "purge removes from external service" do
+  test "purge deletes file from external service" do
     blob = create_blob
 
     blob.purge
     assert_not ActiveStorage::Blob.service.exist?(blob.key)
   end
 
+  test "purge deletes variants from external service" do
+    blob = create_file_blob
+    variant = blob.variant(resize: "100>").processed
+
+    blob.purge
+    assert_not ActiveStorage::Blob.service.exist?(variant.key)
+  end
+
   private
     def expected_url_for(blob, disposition: :inline)
       query_string = { content_type: blob.content_type, disposition: "#{disposition}; #{blob.filename.parameters}" }.to_param
diff --git a/activestorage/test/service/gcs_service_test.rb b/activestorage/test/service/gcs_service_test.rb
index 1860149da9..7efcd60fb7 100644
--- a/activestorage/test/service/gcs_service_test.rb
+++ b/activestorage/test/service/gcs_service_test.rb
@@ -35,6 +35,20 @@ if SERVICE_CONFIGURATIONS[:gcs]
       assert_match(/storage\.googleapis\.com\/.*response-content-disposition=inline.*test\.txt.*response-content-type=text%2Fplain/,
         @service.url(FIXTURE_KEY, expires_in: 2.minutes, disposition: :inline, filename: ActiveStorage::Filename.new("test.txt"), content_type: "text/plain"))
     end
+
+    test "signed URL response headers" do
+      begin
+        key  = SecureRandom.base58(24)
+        data = "Something else entirely!"
+        @service.upload(key, StringIO.new(data), checksum: Digest::MD5.base64digest(data))
+
+        url = @service.url(key, expires_in: 2.minutes, disposition: :inline, filename: ActiveStorage::Filename.new("test.txt"), content_type: "text/plain")
+        response = Net::HTTP.get_response(URI(url))
+        assert_equal "text/plain", response.header["Content-Type"]
+      ensure
+        @service.delete key
+      end
+    end
   end
 else
   puts "Skipping GCS Service tests because no GCS configuration was supplied"
diff --git a/activestorage/test/service/shared_service_tests.rb b/activestorage/test/service/shared_service_tests.rb
index ade91ab89a..ce28c4393a 100644
--- a/activestorage/test/service/shared_service_tests.rb
+++ b/activestorage/test/service/shared_service_tests.rb
@@ -75,5 +75,22 @@ module ActiveStorage::Service::SharedServiceTests
         @service.delete SecureRandom.base58(24)
       end
     end
+
+    test "deleting by prefix" do
+      begin
+        @service.upload("a/a/a", StringIO.new(FIXTURE_DATA))
+        @service.upload("a/a/b", StringIO.new(FIXTURE_DATA))
+        @service.upload("a/b/a", StringIO.new(FIXTURE_DATA))
+
+        @service.delete_prefixed("a/a/")
+        assert_not @service.exist?("a/a/a")
+        assert_not @service.exist?("a/a/b")
+        assert @service.exist?("a/b/a")
+      ensure
+        @service.delete("a/a/a")
+        @service.delete("a/a/b")
+        @service.delete("a/b/a")
+      end
+    end
   end
 end
diff --git a/activesupport/lib/active_support/core_ext/module/concerning.rb b/activesupport/lib/active_support/core_ext/module/concerning.rb
index 370a948eea..800bf213cc 100644
--- a/activesupport/lib/active_support/core_ext/module/concerning.rb
+++ b/activesupport/lib/active_support/core_ext/module/concerning.rb
@@ -22,7 +22,7 @@ class Module
   #
   # == Using comments:
   #
-  #   class Todo
+  #   class Todo < ApplicationRecord
   #     # Other todo implementation
   #     # ...
   #
@@ -42,7 +42,7 @@ class Module
   #
   # Noisy syntax.
   #
-  #   class Todo
+  #   class Todo < ApplicationRecord
   #     # Other todo implementation
   #     # ...
   #
@@ -70,7 +70,7 @@ class Module
   # increased overhead can be a reasonable tradeoff even if it reduces our
   # at-a-glance perception of how things work.
   #
-  #   class Todo
+  #   class Todo < ApplicationRecord
   #     # Other todo implementation
   #     # ...
   #
@@ -82,7 +82,7 @@ class Module
   # By quieting the mix-in noise, we arrive at a natural, low-ceremony way to
   # separate bite-sized concerns.
   #
-  #   class Todo
+  #   class Todo < ApplicationRecord
   #     # Other todo implementation
   #     # ...
   #
@@ -101,7 +101,7 @@ class Module
   #   end
   #
   #   Todo.ancestors
-  #   # => [Todo, Todo::EventTracking, Object]
+  #   # => [Todo, Todo::EventTracking, ApplicationRecord, Object]
   #
   # This small step has some wonderful ripple effects. We can
   # * grok the behavior of our class in one glance,
diff --git a/guides/source/3_2_release_notes.md b/guides/source/3_2_release_notes.md
index f6571544f9..ae6eb27f35 100644
--- a/guides/source/3_2_release_notes.md
+++ b/guides/source/3_2_release_notes.md
@@ -36,7 +36,7 @@ TIP: Note that Ruby 1.8.7 p248 and p249 have marshalling bugs that crash Rails.
     * `coffee-rails ~> 3.2.1`
     * `uglifier >= 1.0.3`
 
-* Rails 3.2 deprecates `vendor/plugins` and Rails 4.0 will remove them completely. You can start replacing these plugins by extracting them as gems and adding them in your Gemfile. If you choose not to make them gems, you can move them into, say, `lib/my_plugin/*` and add an appropriate initializer in `config/initializers/my_plugin.rb`.
+* Rails 3.2 deprecates `vendor/plugins` and Rails 4.0 will remove them completely. You can start replacing these plugins by extracting them as gems and adding them in your `Gemfile`. If you choose not to make them gems, you can move them into, say, `lib/my_plugin/*` and add an appropriate initializer in `config/initializers/my_plugin.rb`.
 
 * There are a couple of new configuration changes you'd want to add in `config/environments/development.rb`:
 
@@ -156,7 +156,7 @@ Railties
 
     will create indexes for `title` and `author` with the latter being a unique index. Some types such as decimal accept custom options. In the example, `price` will be a decimal column with precision and scale set to 7 and 2 respectively.
 
-* Turn gem has been removed from default Gemfile.
+* Turn gem has been removed from default `Gemfile`.
 
 * Remove old plugin generator `rails generate plugin` in favor of `rails plugin new` command.
 
diff --git a/guides/source/4_1_release_notes.md b/guides/source/4_1_release_notes.md
index 6bf65757ec..2c5e665e33 100644
--- a/guides/source/4_1_release_notes.md
+++ b/guides/source/4_1_release_notes.md
@@ -274,7 +274,7 @@ for detailed changes.
 * The [Spring application
   preloader](https://github.com/rails/spring) is now installed
   by default for new applications. It uses the development group of
-  the Gemfile, so will not be installed in
+  the `Gemfile`, so will not be installed in
   production. ([Pull Request](https://github.com/rails/rails/pull/12958))
 
 * `BACKTRACE` environment variable to show unfiltered backtraces for test
diff --git a/guides/source/4_2_release_notes.md b/guides/source/4_2_release_notes.md
index 036a310ac8..7105df5634 100644
--- a/guides/source/4_2_release_notes.md
+++ b/guides/source/4_2_release_notes.md
@@ -368,7 +368,7 @@ Please refer to the [Changelog][railties] for detailed changes.
 
 ### Notable changes
 
-*   Introduced `web-console` in the default application Gemfile.
+*   Introduced `web-console` in the default application `Gemfile`.
     ([Pull Request](https://github.com/rails/rails/pull/11667))
 
 *   Added a `required` option to the model generator for associations.
diff --git a/guides/source/action_view_overview.md b/guides/source/action_view_overview.md
index c1e02745de..fde2040173 100644
--- a/guides/source/action_view_overview.md
+++ b/guides/source/action_view_overview.md
@@ -149,10 +149,10 @@ end
 
 #### Jbuilder
 [Jbuilder](https://github.com/rails/jbuilder) is a gem that's
-maintained by the Rails team and included in the default Rails Gemfile.
+maintained by the Rails team and included in the default Rails `Gemfile`.
 It's similar to Builder, but is used to generate JSON, instead of XML.
 
-If you don't have it, you can add the following to your Gemfile:
+If you don't have it, you can add the following to your `Gemfile`:
 
 ```ruby
 gem 'jbuilder'
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index 3786343fc3..4e28e31a53 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -801,7 +801,7 @@ The SQL that would be executed:
 SELECT * FROM articles WHERE id > 10 ORDER BY id DESC
 
 # Original query without `only`
-SELECT "articles".* FROM "articles" WHERE (id > 10) ORDER BY id desc LIMIT 20
+SELECT * FROM articles WHERE id > 10 ORDER BY id DESC LIMIT 20
 
 ```
 
@@ -820,14 +820,14 @@ Article.find(10).comments.reorder('name')
 The SQL that would be executed:
 
 ```sql
-SELECT * FROM articles WHERE id = 10
+SELECT * FROM articles WHERE id = 10 LIMIT 1
 SELECT * FROM comments WHERE article_id = 10 ORDER BY name
 ```
 
 In the case where the `reorder` clause is not used, the SQL executed would be:
 
 ```sql
-SELECT * FROM articles WHERE id = 10
+SELECT * FROM articles WHERE id = 10 LIMIT 1
 SELECT * FROM comments WHERE article_id = 10 ORDER BY posted_at DESC
 ```
 
@@ -1091,7 +1091,7 @@ This produces:
 
 ```sql
 SELECT articles.* FROM articles
-  INNER JOIN categories ON articles.category_id = categories.id
+  INNER JOIN categories ON categories.id = articles.category_id
   INNER JOIN comments ON comments.article_id = articles.id
 ```
 
@@ -1871,14 +1871,14 @@ All calculation methods work directly on a model:
 
 ```ruby
 Client.count
-# SELECT count(*) AS count_all FROM clients
+# SELECT COUNT(*) FROM clients
 ```
 
 Or on a relation:
 
 ```ruby
 Client.where(first_name: 'Ryan').count
-# SELECT count(*) AS count_all FROM clients WHERE (first_name = 'Ryan')
+# SELECT COUNT(*) FROM clients WHERE (first_name = 'Ryan')
 ```
 
 You can also use various finder methods on a relation for performing complex calculations:
@@ -1890,9 +1890,9 @@ Client.includes("orders").where(first_name: 'Ryan', orders: { status: 'received'
 Which will execute:
 
 ```sql
-SELECT count(DISTINCT clients.id) AS count_all FROM clients
-  LEFT OUTER JOIN orders ON orders.client_id = clients.id WHERE
-  (clients.first_name = 'Ryan' AND orders.status = 'received')
+SELECT COUNT(DISTINCT clients.id) FROM clients
+  LEFT OUTER JOIN orders ON orders.client_id = clients.id
+  WHERE (clients.first_name = 'Ryan' AND orders.status = 'received')
 ```
 
 ### Count
diff --git a/guides/source/asset_pipeline.md b/guides/source/asset_pipeline.md
index 805b0f0d62..e6d5aed135 100644
--- a/guides/source/asset_pipeline.md
+++ b/guides/source/asset_pipeline.md
@@ -35,7 +35,7 @@ rails new appname --skip-sprockets
 ```
 
 Rails automatically adds the `sass-rails`, `coffee-rails` and `uglifier`
-gems to your Gemfile, which are used by Sprockets for asset compression:
+gems to your `Gemfile`, which are used by Sprockets for asset compression:
 
 ```ruby
 gem 'sass-rails'
@@ -44,8 +44,8 @@ gem 'coffee-rails'
 ```
 
 Using the `--skip-sprockets` option will prevent Rails from adding
-them to your Gemfile, so if you later want to enable
-the asset pipeline you will have to add those gems to your Gemfile. Also,
+them to your `Gemfile`, so if you later want to enable
+the asset pipeline you will have to add those gems to your `Gemfile`. Also,
 creating an application with the `--skip-sprockets` option will generate
 a slightly different `config/application.rb` file, with a require statement
 for the sprockets railtie that is commented-out. You will have to remove
@@ -850,7 +850,7 @@ This mode uses more memory, performs more poorly than the default and is not
 recommended.
 
 If you are deploying a production application to a system without any
-pre-existing JavaScript runtimes, you may want to add one to your Gemfile:
+pre-existing JavaScript runtimes, you may want to add one to your `Gemfile`:
 
 ```ruby
 group :production do
diff --git a/guides/source/caching_with_rails.md b/guides/source/caching_with_rails.md
index 31bc478015..780e69c146 100644
--- a/guides/source/caching_with_rails.md
+++ b/guides/source/caching_with_rails.md
@@ -32,7 +32,7 @@ Basic Caching
 This is an introduction to three types of caching techniques: page, action and
 fragment caching. By default Rails provides fragment caching. In order to use
 page and action caching you will need to add `actionpack-page_caching` and
-`actionpack-action_caching` to your Gemfile.
+`actionpack-action_caching` to your `Gemfile`.
 
 By default, caching is only enabled in your production environment. To play
 around with caching locally you'll want to enable caching in your local
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 4bfcc1e21a..fee644d4d4 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -1005,11 +1005,11 @@ Deploying your application using a reverse proxy has definite advantages over tr
 
 Many modern web servers can be used as a proxy server to balance third-party elements such as caching servers or application servers.
 
-One such application server you can use is [Unicorn](http://unicorn.bogomips.org/) to run behind a reverse proxy.
+One such application server you can use is [Unicorn](https://bogomips.org/unicorn/) to run behind a reverse proxy.
 
 In this case, you would need to configure the proxy server (NGINX, Apache, etc) to accept connections from your application server (Unicorn). By default Unicorn will listen for TCP connections on port 8080, but you can change the port or configure it to use sockets instead.
 
-You can find more information in the [Unicorn readme](http://unicorn.bogomips.org/README.html) and understand the [philosophy](http://unicorn.bogomips.org/PHILOSOPHY.html) behind it.
+You can find more information in the [Unicorn readme](https://bogomips.org/unicorn/README.html) and understand the [philosophy](https://bogomips.org/unicorn/PHILOSOPHY.html) behind it.
 
 Once you've configured the application server, you must proxy requests to it by configuring your web server appropriately. For example your NGINX config may include:
 
@@ -1037,7 +1037,7 @@ server {
 }
 ```
 
-Be sure to read the [NGINX documentation](http://nginx.org/en/docs/) for the most up-to-date information.
+Be sure to read the [NGINX documentation](https://nginx.org/en/docs/) for the most up-to-date information.
 
 
 Rails Environment Settings
diff --git a/guides/source/form_helpers.md b/guides/source/form_helpers.md
index 4ce67df93a..f8ec389b01 100644
--- a/guides/source/form_helpers.md
+++ b/guides/source/form_helpers.md
@@ -920,7 +920,7 @@ When an association accepts nested attributes `fields_for` renders its block onc
 ```ruby
 def new
   @person = Person.new
-  2.times { @person.addresses.build}
+  2.times { @person.addresses.build }
 end
 ```
 
diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index e6aa6181cc..2b545e6b82 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -977,7 +977,7 @@ en:
 ```
 
 NOTE: In order to use this helper, you need to install [DynamicForm](https://github.com/joelmoss/dynamic_form)
-gem by adding this line to your Gemfile: `gem 'dynamic_form'`.
+gem by adding this line to your `Gemfile`: `gem 'dynamic_form'`.
 
 ### Translations for Action Mailer E-Mail Subjects
 
diff --git a/guides/source/initialization.md b/guides/source/initialization.md
index 1541ea38cd..c4f1df487b 100644
--- a/guides/source/initialization.md
+++ b/guides/source/initialization.md
@@ -93,7 +93,7 @@ require 'bundler/setup' # Set up gems listed in the Gemfile.
 
 In a standard Rails application, there's a `Gemfile` which declares all
 dependencies of the application. `config/boot.rb` sets
-`ENV['BUNDLE_GEMFILE']` to the location of this file. If the Gemfile
+`ENV['BUNDLE_GEMFILE']` to the location of this file. If the `Gemfile`
 exists, then `bundler/setup` is required. The require is used by Bundler to
 configure the load path for your Gemfile's dependencies.
 
diff --git a/guides/source/testing.md b/guides/source/testing.md
index 8416fd163d..f28c4c224a 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -319,6 +319,8 @@ specify to make your test failure messages clearer.
 | `assert_not_includes( collection, obj, [msg] )`                  | Ensures that `obj` is not in `collection`.|
 | `assert_in_delta( expected, actual, [delta], [msg] )`            | Ensures that the numbers `expected` and `actual` are within `delta` of each other.|
 | `assert_not_in_delta( expected, actual, [delta], [msg] )`        | Ensures that the numbers `expected` and `actual` are not within `delta` of each other.|
+| `assert_in_epsilon ( expected, actual, [epsilon], [msg] )`       | Ensures that the numbers `expected` and `actual` have a relative error less than `epsilon`.|
+| `assert_not_in_epsilon ( expected, actual, [epsilon], [msg] )`   | Ensures that the numbers `expected` and `actual` don't have a relative error less than `epsilon`.|
 | `assert_throws( symbol, [msg] ) { block }`                       | Ensures that the given block throws the symbol.|
 | `assert_raises( exception1, exception2, ... ) { block }`         | Ensures that the given block raises one of the given exceptions.|
 | `assert_instance_of( class, obj, [msg] )`                        | Ensures that `obj` is an instance of `class`.|
@@ -645,7 +647,7 @@ system tests should live.
 
 If you want to change the default settings you can change what the system
 tests are "driven by". Say you want to change the driver from Selenium to
-Poltergeist. First add the `poltergeist` gem to your Gemfile. Then in your
+Poltergeist. First add the `poltergeist` gem to your `Gemfile`. Then in your
 `application_system_test_case.rb` file do the following:
 
 ```ruby
@@ -671,7 +673,8 @@ class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
 end
 ```
 
-If you want to use a headless browser, you could use Headless Chrome by adding `headless_chrome` in the `:using` argument.
+If you want to use a headless browser, you could use Headless Chrome or Headless Firefox by adding
+`headless_chrome` or `headless_firefox` in the `:using` argument.
 
 ```ruby
 require "test_helper"
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 9bc87e4bf0..eae73c3e1b 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -45,7 +45,7 @@ TIP: Ruby 1.8.7 p248 and p249 have marshaling bugs that crash Rails. Ruby Enterp
 ### The Update Task
 
 Rails provides the `app:update` task (`rake rails:update` on 4.2 and earlier). After updating the Rails version
-in the Gemfile, run this task.
+in the `Gemfile`, run this task.
 This will help you with the creation of new files and changes of old files in an
 interactive session.
 
@@ -179,7 +179,7 @@ See [#19034](https://github.com/rails/rails/pull/19034) for more details.
 
 `assigns` and `assert_template` have been extracted to the `rails-controller-testing` gem. To
 continue using these methods in your controller tests, add `gem 'rails-controller-testing'` to
-your Gemfile.
+your `Gemfile`.
 
 If you are using Rspec for testing, please see the extra configuration required in the gem's
 documentation.
@@ -212,7 +212,7 @@ true.
 
 `ActiveModel::Serializers::Xml` has been extracted from Rails to the `activemodel-serializers-xml`
 gem. To continue using XML serialization in your application, add `gem 'activemodel-serializers-xml'`
-to your Gemfile.
+to your `Gemfile`.
 
 ### Removed Support for Legacy `mysql` Database Adapter
 
@@ -278,7 +278,7 @@ You can now just call the dependency once with a wildcard.
 
 ### `ActionView::Helpers::RecordTagHelper` moved to external gem (record_tag_helper)
 
-`content_tag_for` and `div_for` have been removed in favor of just using `content_tag`. To continue using the older methods, add the `record_tag_helper` gem to your Gemfile:
+`content_tag_for` and `div_for` have been removed in favor of just using `content_tag`. To continue using the older methods, add the `record_tag_helper` gem to your `Gemfile`:
 
 ```ruby
 gem 'record_tag_helper', '~> 1.0'
@@ -415,7 +415,7 @@ First, add `gem 'web-console', '~> 2.0'` to the `:development` group in your `Ge
 
 ### Responders
 
-`respond_with` and the class-level `respond_to` methods have been extracted to the `responders` gem. To use them, simply add `gem 'responders', '~> 2.0'` to your Gemfile. Calls to `respond_with` and `respond_to` (again, at the class level) will no longer work without having included the `responders` gem in your dependencies:
+`respond_with` and the class-level `respond_to` methods have been extracted to the `responders` gem. To use them, simply add `gem 'responders', '~> 2.0'` to your `Gemfile`. Calls to `respond_with` and `respond_to` (again, at the class level) will no longer work without having included the `responders` gem in your dependencies:
 
 ```ruby
 # app/controllers/users_controller.rb
@@ -559,7 +559,7 @@ Read the [gem's readme](https://github.com/rails/rails-html-sanitizer) for more
 The documentation for `PermitScrubber` and `TargetScrubber` explains how you
 can gain complete control over when and how elements should be stripped.
 
-If your application needs to use the old sanitizer implementation, include `rails-deprecated_sanitizer` in your Gemfile:
+If your application needs to use the old sanitizer implementation, include `rails-deprecated_sanitizer` in your `Gemfile`:
 
 ```ruby
 gem 'rails-deprecated_sanitizer'
@@ -617,7 +617,7 @@ migration DSL counterpart.
 
 The migration procedure is as follows:
 
-1. remove `gem "foreigner"` from the Gemfile.
+1. remove `gem "foreigner"` from the `Gemfile`.
 2. run `bundle install`.
 3. run `bin/rake db:schema:dump`.
 4. make sure that `db/schema.rb` contains every foreign key definition with
@@ -769,7 +769,7 @@ and has been removed from Rails.
 
 If your application currently depends on MultiJSON directly, you have a few options:
 
-1. Add 'multi_json' to your Gemfile. Note that this might cease to work in the future
+1. Add 'multi_json' to your `Gemfile`. Note that this might cease to work in the future
 
 2. Migrate away from MultiJSON by using `obj.to_json`, and `JSON.parse(str)` instead.
 
@@ -810,7 +810,7 @@ part of the rewrite, the following features have been removed from the encoder:
 
 If your application depends on one of these features, you can get them back by
 adding the [`activesupport-json_encoder`](https://github.com/rails/activesupport-json_encoder)
-gem to your Gemfile.
+gem to your `Gemfile`.
 
 #### JSON representation of Time objects
 
@@ -1135,7 +1135,7 @@ full support for the last few changes in the specification.
 
 ### Gemfile
 
-Rails 4.0 removed the `assets` group from Gemfile. You'd need to remove that
+Rails 4.0 removed the `assets` group from `Gemfile`. You'd need to remove that
 line from your `Gemfile` when upgrading. You should also update your application
 file (in `config/application.rb`):
 
@@ -1147,7 +1147,7 @@ Bundler.require(*Rails.groups)
 
 ### vendor/plugins
 
-Rails 4.0 no longer supports loading plugins from `vendor/plugins`. You must replace any plugins by extracting them to gems and adding them to your Gemfile. If you choose not to make them gems, you can move them into, say, `lib/my_plugin/*` and add an appropriate initializer in `config/initializers/my_plugin.rb`.
+Rails 4.0 no longer supports loading plugins from `vendor/plugins`. You must replace any plugins by extracting them to gems and adding them to your `Gemfile`. If you choose not to make them gems, you can move them into, say, `lib/my_plugin/*` and add an appropriate initializer in `config/initializers/my_plugin.rb`.
 
 ### Active Record
 
@@ -1214,7 +1214,7 @@ end
 
 ### Active Resource
 
-Rails 4.0 extracted Active Resource to its own gem. If you still need the feature you can add the [Active Resource gem](https://github.com/rails/activeresource) in your Gemfile.
+Rails 4.0 extracted Active Resource to its own gem. If you still need the feature you can add the [Active Resource gem](https://github.com/rails/activeresource) in your `Gemfile`.
 
 ### Active Model
 
@@ -1414,7 +1414,7 @@ config.active_record.mass_assignment_sanitizer = :strict
 
 ### vendor/plugins
 
-Rails 3.2 deprecates `vendor/plugins` and Rails 4.0 will remove them completely. While it's not strictly necessary as part of a Rails 3.2 upgrade, you can start replacing any plugins by extracting them to gems and adding them to your Gemfile. If you choose not to make them gems, you can move them into, say, `lib/my_plugin/*` and add an appropriate initializer in `config/initializers/my_plugin.rb`.
+Rails 3.2 deprecates `vendor/plugins` and Rails 4.0 will remove them completely. While it's not strictly necessary as part of a Rails 3.2 upgrade, you can start replacing any plugins by extracting them to gems and adding them to your `Gemfile`. If you choose not to make them gems, you can move them into, say, `lib/my_plugin/*` and add an appropriate initializer in `config/initializers/my_plugin.rb`.
 
 ### Active Record
 
diff --git a/guides/source/working_with_javascript_in_rails.md b/guides/source/working_with_javascript_in_rails.md
index 86746a5ae0..c3dff1772c 100644
--- a/guides/source/working_with_javascript_in_rails.md
+++ b/guides/source/working_with_javascript_in_rails.md
@@ -492,7 +492,7 @@ replace the entire `<body>` of the page with the `<body>` of the response. It
 will then use PushState to change the URL to the correct one, preserving
 refresh semantics and giving you pretty URLs.
 
-The only thing you have to do to enable Turbolinks is have it in your Gemfile,
+The only thing you have to do to enable Turbolinks is have it in your `Gemfile`,
 and put `//= require turbolinks` in your JavaScript manifest, which is usually
 `app/assets/javascripts/application.js`.
 
diff --git a/railties/lib/rails/generators/rails/app/templates/Gemfile.tt b/railties/lib/rails/generators/rails/app/templates/Gemfile.tt
index 61026f5182..e3ed3e7c11 100644
--- a/railties/lib/rails/generators/rails/app/templates/Gemfile.tt
+++ b/railties/lib/rails/generators/rails/app/templates/Gemfile.tt
@@ -41,13 +41,6 @@ gem 'bootsnap', '>= 1.1.0', require: false
 group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
   gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
-  <%- if depends_on_system_test? -%>
-  # Adds support for Capybara system testing and selenium driver
-  gem 'capybara', '~> 2.15'
-  gem 'selenium-webdriver'
-  # Easy installation and use of chromedriver to run system tests with Chrome
-  gem 'chromedriver-helper'
-  <%- end -%>
 end
 
 group :development do
@@ -70,6 +63,16 @@ group :development do
 <% end -%>
 <% end -%>
 end
+
+<%- if depends_on_system_test? -%>
+group :test do
+  # Adds support for Capybara system testing and selenium driver
+  gem 'capybara', '~> 2.15'
+  gem 'selenium-webdriver'
+  # Easy installation and use of chromedriver to run system tests with Chrome
+  gem 'chromedriver-helper'
+end
+<%- end -%>
 <% end -%>
 
 # Windows does not include zoneinfo files, so bundle the tzinfo-data gem
diff --git a/railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt
index 1e19380dcb..a5eccf816b 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt
@@ -26,31 +26,9 @@ environment ENV.fetch("RAILS_ENV") { "development" }
 # Use the `preload_app!` method when specifying a `workers` number.
 # This directive tells Puma to first boot the application and load code
 # before forking the application. This takes advantage of Copy On Write
-# process behavior so workers use less memory. If you use this option
-# you need to make sure to reconnect any threads in the `on_worker_boot`
-# block.
+# process behavior so workers use less memory.
 #
 # preload_app!
 
-# If you are preloading your application and using Active Record, it's
-# recommended that you close any connections to the database before workers
-# are forked to prevent connection leakage.
-#
-# before_fork do
-#   ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
-# end
-
-# The code in the `on_worker_boot` will be called if you are using
-# clustered mode by specifying a number of `workers`. After each worker
-# process is booted, this block will be run. If you are using the `preload_app!`
-# option, you will want to use this block to reconnect to any threads
-# or connections that may have been created at application boot, as Ruby
-# cannot share connections between processes.
-#
-# on_worker_boot do
-#   ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
-# end
-#
-
 # Allow puma to be restarted by `rails restart` command.
 plugin :tmp_restart
diff --git a/railties/test/application/rake/dbs_test.rb b/railties/test/application/rake/dbs_test.rb
index 0235210fdd..2082e9fa9f 100644
--- a/railties/test/application/rake/dbs_test.rb
+++ b/railties/test/application/rake/dbs_test.rb
@@ -98,6 +98,20 @@ module ApplicationTests
         end
       end
 
+      test "db:create works when schema cache exists and database does not exist" do
+        use_postgresql
+
+        begin
+          rails %w(db:create db:migrate db:schema:cache:dump)
+
+          rails "db:drop"
+          rails "db:create"
+          assert_equal 0, $?.exitstatus
+        ensure
+          rails "db:drop" rescue nil
+        end
+      end
+
       test "db:drop failure because database does not exist" do
         output = rails("db:drop:_unsafe", "--trace")
         assert_match(/does not exist/, output)
diff --git a/railties/test/generators/app_generator_test.rb b/railties/test/generators/app_generator_test.rb
index 774fd0f315..96803db838 100644
--- a/railties/test/generators/app_generator_test.rb
+++ b/railties/test/generators/app_generator_test.rb
@@ -310,7 +310,7 @@ class AppGeneratorTest < Rails::Generators::TestCase
       case command
       when "active_storage:install"
         @binstub_called += 1
-        assert_equal 1, @binstub_called, "active_storage:install expected to be called once, but was called #{@install_called} times."
+        assert_equal 1, @binstub_called, "active_storage:install expected to be called once, but was called #{@binstub_called} times"
       end
     end
 
@@ -743,6 +743,41 @@ class AppGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_webpack_option
+    command_check = -> command, *_ do
+      @called ||= 0
+      if command == "webpacker:install"
+        @called += 1
+        assert_equal 1, @called, "webpacker:install expected to be called once, but was called #{@called} times."
+      end
+    end
+
+    generator([destination_root], webpack: "webpack").stub(:rails_command, command_check) do
+      quietly { generator.invoke_all }
+    end
+
+    assert_gem "webpacker"
+  end
+
+  def test_webpack_option_with_js_framework
+    command_check = -> command, *_ do
+      case command
+      when "webpacker:install"
+        @webpacker ||= 0
+        @webpacker += 1
+        assert_equal 1, @webpacker, "webpacker:install expected to be called once, but was called #{@webpacker} times."
+      when "webpacker:install:react"
+        @react ||= 0
+        @react += 1
+        assert_equal 1, @react, "webpacker:install:react expected to be called once, but was called #{@react} times."
+      end
+    end
+
+    generator([destination_root], webpack: "react").stub(:rails_command, command_check) do
+      quietly { generator.invoke_all }
+    end
+  end
+
   def test_generator_if_skip_turbolinks_is_given
     run_generator [destination_root, "--skip-turbolinks"]
 
diff --git a/railties/test/isolation/abstract_unit.rb b/railties/test/isolation/abstract_unit.rb
index 7522237a38..5b1c06d4e5 100644
--- a/railties/test/isolation/abstract_unit.rb
+++ b/railties/test/isolation/abstract_unit.rb
@@ -381,6 +381,21 @@ module TestHelpers
 
       $:.reject! { |path| path =~ %r'/(#{to_remove.join('|')})/' }
     end
+
+    def use_postgresql
+      File.open("#{app_path}/config/database.yml", "w") do |f|
+        f.puts <<-YAML
+        default: &default
+          adapter: postgresql
+          pool: 5
+          database: railties_test
+        development:
+          <<: *default
+        test:
+          <<: *default
+        YAML
+      end
+    end
   end
 end