Merge pull request #30773 from y-yagi/fix_30765

Make automatically synchronize test schema work inside engine

activerecord/lib/active_record/migration.rb

@@ -581,7 +581,8 @@ def check_pending!(connection = Base.connection)
       def load_schema_if_pending!
         if ActiveRecord::Migrator.needs_migration? || !ActiveRecord::Migrator.any_migrations?
           # Roundtrip to Rake to allow plugins to hook into database initialization.
-          FileUtils.cd Rails.root do
+          root = defined?(ENGINE_ROOT) ? ENGINE_ROOT : Rails.root
+          FileUtils.cd(root) do
             current_config = Base.connection_config
             Base.clear_all_connections!
             system("bin/rails db:test:prepare")

railties/lib/rails/tasks/engine.rake

@@ -70,6 +70,9 @@ namespace :db do
 
   desc "Retrieves the current schema version number"
   app_task "version"
+
+  # desc 'Load the test schema'
+  app_task "test:prepare"
 end
 
 def find_engine_path(path)

railties/test/engine/test_test.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+
+class Rails::Engine::TestTest < ActiveSupport::TestCase
+  setup do
+    @destination_root = Dir.mktmpdir("bukkits")
+    Dir.chdir(@destination_root) { `bundle exec rails plugin new bukkits --mountable` }
+  end
+
+  teardown do
+    FileUtils.rm_rf(@destination_root)
+  end
+
+  test "automatically synchronize test schema" do
+    Dir.chdir(plugin_path) do
+      # In order to confirm that migration files are loaded, generate multiple migration files.
+      `bin/rails generate model user name:string;
+       bin/rails generate model todo name:string;
+       RAILS_ENV=development bin/rails db:migrate`
+
+      output = `bin/rails test test/models/bukkits/user_test.rb`
+      assert_includes(output, "0 runs, 0 assertions, 0 failures, 0 errors, 0 skips")
+    end
+  end
+
+  private
+    def plugin_path
+      "#{@destination_root}/bukkits"
+    end
+end