Fix migration ordering for bin/rails db:prepare across databases

Author: fatkodima

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -192,9 +192,17 @@ def prepare_all
 
               seed = true
             end
+          end
+        end
 
-            migrate
-            dump_schema(db_config) if ActiveRecord.dump_schema_after_migration
+        each_current_environment(env) do |environment|
+          db_configs_with_versions(environment).sort.each do |version, db_configs|
+            db_configs.each do |db_config|
+              with_temporary_pool(db_config) do
+                migrate(version)
+                dump_schema(db_config) if ActiveRecord.dump_schema_after_migration
+              end
+            end
           end
         end
 
@@ -255,10 +263,10 @@ def migrate(version = nil)
         Migration.verbose = verbose_was
       end
 
-      def db_configs_with_versions # :nodoc:
+      def db_configs_with_versions(environment = env) # :nodoc:
         db_configs_with_versions = Hash.new { |h, k| h[k] = [] }
 
-        with_temporary_pool_for_each do |pool|
+        with_temporary_pool_for_each(env: environment) do |pool|
           db_config = pool.db_config
           versions_to_run = pool.migration_context.pending_migration_versions
           target_version = ActiveRecord::Tasks::DatabaseTasks.target_version
@@ -580,10 +588,7 @@ def class_for_adapter(adapter)
         end
 
         def each_current_configuration(environment, name = nil)
-          environments = [environment]
-          environments << "test" if environment == "development" && !ENV["SKIP_TEST_DATABASE"] && !ENV["DATABASE_URL"]
-
-          environments.each do |env|
+          each_current_environment(environment) do |env|
             configs_for(env_name: env).each do |db_config|
               next if name && name != db_config.name
 
@@ -592,6 +597,12 @@ def each_current_configuration(environment, name = nil)
           end
         end
 
+        def each_current_environment(environment, &block)
+          environments = [environment]
+          environments << "test" if environment == "development" && !ENV["SKIP_TEST_DATABASE"] && !ENV["DATABASE_URL"]
+          environments.each(&block)
+        end
+
         def each_local_configuration
           configs_for.each do |db_config|
             next unless db_config.database

railties/test/application/rake/multi_dbs_test.rb

@@ -566,6 +566,35 @@ class ThreeMigration < ActiveRecord::Migration::Current
         end
       end
 
+      test "db:prepare respects timestamp ordering across databases" do
+        require "#{app_path}/config/environment"
+        app_file "db/migrate/01_one_migration.rb", <<-MIGRATION
+          class OneMigration < ActiveRecord::Migration::Current
+          end
+        MIGRATION
+
+        app_file "db/animals_migrate/02_two_migration.rb", <<-MIGRATION
+          class TwoMigration < ActiveRecord::Migration::Current
+          end
+        MIGRATION
+
+        app_file "db/animals_migrate/04_four_migration.rb", <<-MIGRATION
+        class FourMigration < ActiveRecord::Migration::Current
+        end
+        MIGRATION
+
+        app_file "db/migrate/03_three_migration.rb", <<-MIGRATION
+          class ThreeMigration < ActiveRecord::Migration::Current
+          end
+        MIGRATION
+
+        Dir.chdir(app_path) do
+          output = rails "db:prepare"
+          entries = output.scan(/^== (\d+).+migrated/).map(&:first).map(&:to_i)
+          assert_equal [1, 2, 3, 4] * 2, entries # twice because for test env too
+        end
+      end
+
       test "migrations in different directories can have the same timestamp" do
         require "#{app_path}/config/environment"
         app_file "db/migrate/01_one_migration.rb", <<-MIGRATION