Automatically maintain test database schema

* Move check from generated helper to test_help.rb, so that all
  applications can benefit
* Rather than just raising when the test schema has pending migrations,
  try to load in the schema and only raise if there are pending
  migrations afterwards
* Opt out of the check by setting
  config.active_record.maintain_test_schema = false
* Deprecate db:test:* tasks. The test helper is now fully responsible
  for maintaining the test schema, so we don't need rake tasks for this.
  This is also a speed improvement since we're no longer reloading the
  test database on every call to "rake test".

3 files changed, 57 insertions, 3 deletions

diff --git a/railties/test/application/rake/dbs_test.rb b/railties/test/application/rake/dbs_test.rb
index 3dce315d3a..66d3137df0 100644
--- a/railties/test/application/rake/dbs_test.rb
+++ b/railties/test/application/rake/dbs_test.rb
@@ -174,6 +174,15 @@ module ApplicationTests
         require "#{app_path}/config/environment"
         db_test_load_structure
       end
+
+      test 'db:test deprecation' do
+        require "#{app_path}/config/environment"
+        Dir.chdir(app_path) do
+          output = `bundle exec rake db:migrate db:test:prepare 2>&1`
+          assert_equal "WARNING: db:test:prepare is deprecated. The Rails test helper now maintains " \
+                       "your test schema automatically, see the release notes for details.\n", output
+        end
+      end
     end
   end
 end
diff --git a/railties/test/application/rake_test.rb b/railties/test/application/rake_test.rb
index 33d3c4a19e..317e73245c 100644
--- a/railties/test/application/rake_test.rb
+++ b/railties/test/application/rake_test.rb
@@ -187,7 +187,7 @@ module ApplicationTests
     def test_scaffold_tests_pass_by_default
       output = Dir.chdir(app_path) do
         `rails generate scaffold user username:string password:string;
-         bundle exec rake db:migrate db:test:clone test`
+         bundle exec rake db:migrate test`
       end
 
       assert_match(/7 runs, 13 assertions, 0 failures, 0 errors/, output)
@@ -197,7 +197,7 @@ module ApplicationTests
     def test_scaffold_with_references_columns_tests_pass_by_default
       output = Dir.chdir(app_path) do
         `rails generate scaffold LineItems product:references cart:belongs_to;
-         bundle exec rake db:migrate db:test:clone test`
+         bundle exec rake db:migrate test`
       end
 
       assert_match(/7 runs, 13 assertions, 0 failures, 0 errors/, output)
diff --git a/railties/test/application/test_test.rb b/railties/test/application/test_test.rb
index 6f2f328588..a223180169 100644
--- a/railties/test/application/test_test.rb
+++ b/railties/test/application/test_test.rb
@@ -67,10 +67,55 @@ module ApplicationTests
       assert_match %r{/app/test/unit/failing_test\.rb}, output
     end
 
+    test "migrations" do
+      output  = script('generate model user name:string')
+      version = output.match(/(\d+)_create_users\.rb/)[1]
+
+      app_file 'test/models/user_test.rb', <<-RUBY
+        require 'test_helper'
+
+        class UserTest < ActiveSupport::TestCase
+          test "user" do
+            User.create! name: "Jon"
+          end
+        end
+      RUBY
+      app_file 'db/schema.rb', ''
+
+      assert_unsuccessful_run "models/user_test.rb", "Migrations are pending"
+
+      app_file 'db/schema.rb', <<-RUBY
+        ActiveRecord::Schema.define(version: #{version}) do
+          create_table :users do |t|
+            t.string :name
+          end
+        end
+      RUBY
+
+      app_file 'config/initializers/disable_maintain_test_schema.rb', <<-RUBY
+        Rails.application.config.active_record.maintain_test_schema = false
+      RUBY
+
+      assert_unsuccessful_run "models/user_test.rb", "Could not find table 'users'"
+
+      File.delete "#{app_path}/config/initializers/disable_maintain_test_schema.rb"
+
+      result = assert_successful_test_run('models/user_test.rb')
+      assert !result.include?("create_table(:users)")
+    end
+
     private
+      def assert_unsuccessful_run(name, message)
+        result = run_test_file(name)
+        assert_not_equal 0, $?.to_i
+        assert result.include?(message)
+        result
+      end
+
       def assert_successful_test_run(name)
         result = run_test_file(name)
         assert_equal 0, $?.to_i, result
+        result
       end
 
       def run_test_file(name, options = {})
@@ -83,7 +128,7 @@ module ApplicationTests
         env["RUBYLIB"] = $:.join(':')
 
         Dir.chdir(app_path) do
-          `#{env_string(env)} #{Gem.ruby} #{args.join(' ')}`
+          `#{env_string(env)} #{Gem.ruby} #{args.join(' ')} 2>&1`
         end
       end