Turn on performance based cops

Use attr_reader/attr_writer instead of methods

method is 12% slower

Use flat_map over map.flatten(1)

flatten is 66% slower

Use hash[]= instead of hash.merge! with single arguments

merge! is 166% slower

See https://github.com/rails/rails/pull/32337 for more conversation

4 files changed, 9 insertions, 7 deletions

diff --git a/actionpack/test/controller/http_digest_authentication_test.rb b/actionpack/test/controller/http_digest_authentication_test.rb
index 3f211cd60d..b133afb343 100644
--- a/actionpack/test/controller/http_digest_authentication_test.rb
+++ b/actionpack/test/controller/http_digest_authentication_test.rb
@@ -272,7 +272,7 @@ class HttpDigestAuthenticationTest < ActionController::TestCase
       credentials.merge!(options)
       path_info = @request.env["PATH_INFO"].to_s
       uri = options[:uri] || path_info
-      credentials.merge!(uri: uri)
+      credentials[:uri] = uri
       @request.env["ORIGINAL_FULLPATH"] = path_info
       ActionController::HttpAuthentication::Digest.encode_credentials(method, credentials, password, options[:password_is_ha1])
     end
diff --git a/actionpack/test/controller/log_subscriber_test.rb b/actionpack/test/controller/log_subscriber_test.rb
index be455642de..0562c16284 100644
--- a/actionpack/test/controller/log_subscriber_test.rb
+++ b/actionpack/test/controller/log_subscriber_test.rb
@@ -82,9 +82,7 @@ module Another
       @last_payload = payload
     end
 
-    def last_payload
-      @last_payload
-    end
+    attr_reader :last_payload
   end
 end
 
diff --git a/actionpack/test/controller/resources_test.rb b/actionpack/test/controller/resources_test.rb
index 3688fdbeee..d336b96eff 100644
--- a/actionpack/test/controller/resources_test.rb
+++ b/actionpack/test/controller/resources_test.rb
@@ -1322,7 +1322,7 @@ class ResourcesTest < ActionController::TestCase
     def assert_resource_allowed_routes(controller, options, shallow_options, allowed, not_allowed, path = controller)
       shallow_path = "#{path}/#{shallow_options[:id]}"
       format = options[:format] && ".#{options[:format]}"
-      options.merge!(controller: controller)
+      options[:controller] = controller
       shallow_options.merge!(options)
 
       assert_whether_allowed(allowed, not_allowed, options,         "index",    "#{path}#{format}",               :get)
@@ -1336,7 +1336,7 @@ class ResourcesTest < ActionController::TestCase
 
     def assert_singleton_resource_allowed_routes(controller, options, allowed, not_allowed, path = controller.singularize)
       format = options[:format] && ".#{options[:format]}"
-      options.merge!(controller: controller)
+      options[:controller] = controller
 
       assert_whether_allowed(allowed, not_allowed, options, "new",      "#{path}/new#{format}",   :get)
       assert_whether_allowed(allowed, not_allowed, options, "create",   "#{path}#{format}",       :post)
diff --git a/actionpack/test/dispatch/header_test.rb b/actionpack/test/dispatch/header_test.rb
index 3a265a056b..43e63eb996 100644
--- a/actionpack/test/dispatch/header_test.rb
+++ b/actionpack/test/dispatch/header_test.rb
@@ -105,16 +105,20 @@ class HeaderTest < ActiveSupport::TestCase
   end
 
   test "#merge! headers with mutation" do
+    # rubocop:disable Performance/RedundantMerge
     @headers.merge!("Host" => "http://example.test",
                     "Content-Type" => "text/html")
+    # rubocop:enable Performance/RedundantMerge
     assert_equal({ "HTTP_HOST" => "http://example.test",
                   "CONTENT_TYPE" => "text/html",
                   "HTTP_REFERER" => "/some/page" }, @headers.env)
   end
 
   test "#merge! env with mutation" do
+    # rubocop:disable Performance/RedundantMerge
     @headers.merge!("HTTP_HOST" => "http://first.com",
                     "CONTENT_TYPE" => "text/html")
+    # rubocop:enable Performance/RedundantMerge
     assert_equal({ "HTTP_HOST" => "http://first.com",
                   "CONTENT_TYPE" => "text/html",
                   "HTTP_REFERER" => "/some/page" }, @headers.env)
@@ -156,7 +160,7 @@ class HeaderTest < ActiveSupport::TestCase
     env = { "HTTP_REFERER" => "/" }
     headers = make_headers(env)
     headers["Referer"] = "http://example.com/"
-    headers.merge! "CONTENT_TYPE" => "text/plain"
+    headers["CONTENT_TYPE"] = "text/plain"
     assert_equal({ "HTTP_REFERER" => "http://example.com/",
                   "CONTENT_TYPE" => "text/plain" }, env)
   end