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".

activerecord/CHANGELOG.md

@@ -1,3 +1,12 @@
+*   Since the `test_help.rb` in Railties now automatically maintains
+    your test schema, the `rake db:test:*` tasks are deprecated. This
+    doesn't stop you manually running other tasks on your test database
+    if needed:
+
+        rake db:schema:load RAILS_ENV=test
+
+    *Jon Leighton*
+
 *   Fix presence validator for association when the associated record responds to `to_a`.
 
     *gmarik*
@@ -54,6 +63,8 @@
 *   Deprecated use of string argument as a configuration lookup in
     `ActiveRecord::Base.establish_connection`. Instead, a symbol must be given.
 
+*   Deprecated use of string argument as a configuration lookup in `ActiveRecord::Base.establish_connection`. Instead, a symbol must be given.
+
     *José Valim*
 
 *   Fixed `update_column`, `update_columns`, and `update_all` to correctly serialize

activerecord/lib/active_record/core.rb

@@ -69,6 +69,9 @@ module ActiveRecord
       mattr_accessor :timestamped_migrations, instance_writer: false
       self.timestamped_migrations = true
 
+      # :nodoc:
+      mattr_accessor :maintain_test_schema, instance_accessor: false
+
       def self.disable_implicit_join_references=(value)
         ActiveSupport::Deprecation.warn("Implicit join references were removed with Rails 4.1." \
                                         "Make sure to remove this configuration because it does nothing.")

activerecord/lib/active_record/migration.rb

@@ -389,6 +389,19 @@ module ActiveRecord
         raise ActiveRecord::PendingMigrationError if ActiveRecord::Migrator.needs_migration?
       end
 
+      def load_schema_if_pending!
+        if ActiveRecord::Migrator.needs_migration?
+          ActiveRecord::Tasks::DatabaseTasks.load_schema
+          check_pending!
+        end
+      end
+
+      def maintain_test_schema! # :nodoc:
+        if ActiveRecord::Base.maintain_test_schema
+          suppress_messages { load_schema_if_pending! }
+        end
+      end
+
       def method_missing(name, *args, &block) # :nodoc:
         (delegate || superclass.delegate).send(name, *args, &block)
       end

activerecord/lib/active_record/railtie.rb

@@ -31,22 +31,15 @@ module ActiveRecord
 
 
     config.active_record.use_schema_cache_dump = true
+    config.active_record.maintain_test_schema = true
 
     config.eager_load_namespaces << ActiveRecord
 
     rake_tasks do
       require "active_record/base"
 
-      ActiveRecord::Tasks::DatabaseTasks.seed_loader = Rails.application
-      ActiveRecord::Tasks::DatabaseTasks.env = Rails.env
-
       namespace :db do
         task :load_config do
-          ActiveRecord::Tasks::DatabaseTasks.db_dir = Rails.application.config.paths["db"].first
-          ActiveRecord::Tasks::DatabaseTasks.migrations_paths = Rails.application.paths['db/migrate'].to_a
-          ActiveRecord::Tasks::DatabaseTasks.fixtures_path = File.join Rails.root, 'test', 'fixtures'
-          ActiveRecord::Tasks::DatabaseTasks.root = Rails.root
-
           configuration = if ENV["DATABASE_URL"]
             { Rails.env => ENV["DATABASE_URL"] }
           else

activerecord/lib/active_record/railties/databases.rake

@@ -234,9 +234,7 @@ db_namespace = namespace :db do
 
     desc 'Load a schema.rb file into the database'
     task :load => [:environment, :load_config] do
-      file = ENV['SCHEMA'] || File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, 'schema.rb')
+      ActiveRecord::Tasks::DatabaseTasks.load_schema(:ruby, ENV['SCHEMA'])
-      ActiveRecord::Tasks::DatabaseTasks.check_schema_file(file)
-      load(file)
     end
 
     task :load_if_ruby => ['db:create', :environment] do
@@ -281,10 +279,7 @@ db_namespace = namespace :db do
 
     # desc "Recreate the databases from the structure.sql file"
     task :load => [:environment, :load_config] do
-      filename = ENV['DB_STRUCTURE'] || File.join(ActiveRecord::Tasks::DatabaseTasks.db_dir, "structure.sql")
+      ActiveRecord::Tasks::DatabaseTasks.load_schema(:sql, ENV['DB_STRUCTURE'])
-      ActiveRecord::Tasks::DatabaseTasks.check_schema_file(filename)
-      current_config = ActiveRecord::Tasks::DatabaseTasks.current_config
-      ActiveRecord::Tasks::DatabaseTasks.structure_load(current_config, filename)
     end
 
     task :load_if_sql => ['db:create', :environment] do
@@ -294,8 +289,15 @@ db_namespace = namespace :db do
 
   namespace :test do
 
+    task :deprecated do
+      Rake.application.top_level_tasks.grep(/^db:test:/).each do |task|
+        $stderr.puts "WARNING: #{task} is deprecated. The Rails test helper now maintains " \
+                     "your test schema automatically, see the release notes for details."
+      end
+    end
+
     # desc "Recreate the test database from the current schema"
-    task :load => 'db:test:purge' do
+    task :load => %w(db:test:deprecated db:test:purge) do
       case ActiveRecord::Base.schema_format
         when :ruby
           db_namespace["test:load_schema"].invoke
@@ -305,7 +307,7 @@ db_namespace = namespace :db do
     end
 
     # desc "Recreate the test database from an existent schema.rb file"
-    task :load_schema => 'db:test:purge' do
+    task :load_schema => %w(db:test:deprecated db:test:purge) do
       begin
         should_reconnect = ActiveRecord::Base.connection_pool.active_connection?
         ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations['test'])
@@ -319,7 +321,7 @@ db_namespace = namespace :db do
     end
 
     # desc "Recreate the test database from an existent structure.sql file"
-    task :load_structure => 'db:test:purge' do
+    task :load_structure => %w(db:test:deprecated db:test:purge) do
       begin
         ActiveRecord::Tasks::DatabaseTasks.current_config(:config => ActiveRecord::Base.configurations['test'])
         db_namespace["structure:load"].invoke
@@ -329,7 +331,7 @@ db_namespace = namespace :db do
     end
 
     # desc "Recreate the test database from a fresh schema"
-    task :clone => :environment do
+    task :clone => %w(db:test:deprecated environment) do
       case ActiveRecord::Base.schema_format
         when :ruby
           db_namespace["test:clone_schema"].invoke
@@ -339,18 +341,18 @@ db_namespace = namespace :db do
     end
 
     # desc "Recreate the test database from a fresh schema.rb file"
-    task :clone_schema => ["db:schema:dump", "db:test:load_schema"]
+    task :clone_schema => %w(db:test:deprecated db:schema:dump db:test:load_schema)
 
     # desc "Recreate the test database from a fresh structure.sql file"
-    task :clone_structure => [ "db:structure:dump", "db:test:load_structure" ]
+    task :clone_structure => %w(db:structure:dump db:test:load_structure)
 
     # desc "Empty the test database"
-    task :purge => [:environment, :load_config] do
+    task :purge => %w(db:test:deprecated environment load_config) do
       ActiveRecord::Tasks::DatabaseTasks.purge ActiveRecord::Base.configurations['test']
     end
 
     # desc 'Check for pending migrations and load the test schema'
-    task :prepare => [:environment, :load_config] do
+    task :prepare => %w(db:test:deprecated environment load_config) do
       unless ActiveRecord::Base.configurations.blank?
         db_namespace['test:load'].invoke
       end
@@ -385,5 +387,3 @@ namespace :railties do
     end
   end
 end
-
-task 'test:prepare' => ['db:test:prepare', 'db:test:load', 'db:abort_if_pending_migrations']

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -36,9 +36,8 @@ module ActiveRecord
     module DatabaseTasks
       extend self
 
-      attr_writer :current_config
+      attr_writer :current_config, :db_dir, :migrations_paths, :fixtures_path, :root, :env, :seed_loader
-      attr_accessor :database_configuration, :migrations_paths, :seed_loader, :db_dir,
+      attr_accessor :database_configuration
-                    :fixtures_path, :env, :root
 
       LOCAL_HOSTS    = ['127.0.0.1', 'localhost']
 
@@ -51,6 +50,30 @@ module ActiveRecord
       register_task(/postgresql/,   ActiveRecord::Tasks::PostgreSQLDatabaseTasks)
       register_task(/sqlite/,       ActiveRecord::Tasks::SQLiteDatabaseTasks)
 
+      def db_dir
+        @db_dir ||= Rails.application.config.paths["db"].first
+      end
+
+      def migrations_paths
+        @migrations_paths ||= Rails.application.paths['db/migrate'].to_a
+      end
+
+      def fixtures_path
+        @fixtures_path ||= File.join(root, 'test', 'fixtures')
+      end
+
+      def root
+        @root ||= Rails.root
+      end
+
+      def env
+        @env ||= Rails.env
+      end
+
+      def seed_loader
+        @seed_loader ||= Rails.application
+      end
+
       def current_config(options = {})
         options.reverse_merge! :env => env
         if options.has_key?(:config)
@@ -133,6 +156,21 @@ module ActiveRecord
         class_for_adapter(configuration['adapter']).new(*arguments).structure_load(filename)
       end
 
+      def load_schema(format = ActiveRecord::Base.schema_format, file = nil)
+        case format
+        when :ruby
+          file ||= File.join(db_dir, "schema.rb")
+          check_schema_file(file)
+          load(file)
+        when :sql
+          file ||= File.join(db_dir, "structure.sql")
+          check_schema_file(file)
+          structure_load(current_config, file)
+        else
+          raise ArgumentError, "unknown format #{format.inspect}"
+        end
+      end
+
       def check_schema_file(filename)
         unless File.exist?(filename)
           message = %{#{filename} doesn't exist yet. Run `rake db:migrate` to create it, then try again.}

guides/source/4_1_release_notes.md

@@ -281,6 +281,13 @@ for detailed changes.
 * Add `Application#message_verifier` method to return a message
   verifier. ([Pull Request](https://github.com/rails/rails/pull/12995))
 
+* The `test_help.rb` file which is required by the default generated test
+  helper will automatically keep your test database up-to-date with
+  `db/schema.rb` (or `db/structure.sql`). It raises an error if
+  reloading the schema does not resolve all pending migrations. Opt out
+  with `config.active_record.maintain_test_schema = false`. ([Pull
+  Request](https://github.com/rails/rails/pull/13528))
+
 Action Pack
 -----------
 
@@ -421,6 +428,10 @@ for detailed changes.
 * Deprecated `ConnectionAdapters::SchemaStatements#distinct`,
   as it is no longer used by internals. ([Pull Request](https://github.com/rails/rails/pull/10556))
 
+* Deprecated `rake db:test:*` tasks as the test database is now
+  automatically maintained. See railties release notes. ([Pull
+  Request](https://github.com/rails/rails/pull/13528))
+
 ### Notable changes
 
 * Added `ActiveRecord::Base.to_param` for convenient "pretty" URLs derived from

guides/source/configuring.md

@@ -290,6 +290,8 @@ All these configuration options are delegated to the `I18n` library.
 
 * `config.active_record.attribute_types_cached_by_default` sets the attribute types that `ActiveRecord::AttributeMethods` will cache by default on reads. The default is `[:datetime, :timestamp, :time, :date]`.
 
+* `config.active_record.maintain_test_schema` is a boolean value which controls whether Active Record should try to keep your test database schema up-to-date with `db/schema.rb` (or `db/structure.sql`) when you run your tests. The default is true.
+
 The MySQL adapter adds one additional configuration option:
 
 * `ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans` controls whether Active Record will consider all `tinyint(1)` columns in a MySQL database to be booleans and is true by default.

guides/source/plugins.md

@@ -224,7 +224,6 @@ and migrating the database. First, run:
 ```bash
 $ cd test/dummy
 $ rake db:migrate
-$ rake db:test:prepare
 ```
 
 While you are here, change the Hickwall and Wickwall models so that they know that they are supposed to act

guides/source/testing.md

@@ -211,31 +211,9 @@ This line of code is called an _assertion_. An assertion is a line of code that
 
 Every test contains one or more assertions. Only when all the assertions are successful will the test pass.
 
-### Preparing your Application for Testing
+### Maintaining the test database schema
 
-Before you can run your tests, you need to ensure that the test database structure is current. For this you can use the following rake commands:
+In order to run your tests, your test database will need to have the current structure. The test helper checks whether your test database has any pending migrations. If so, it will try to load your `db/schema.rb` or `db/structure.sql` into the test database. If migrations are still pending, an error will be raised.
-
-```bash
-$ rake db:migrate
-...
-$ rake db:test:load
-```
-
-The `rake db:migrate` above runs any pending migrations on the _development_ environment and updates `db/schema.rb`. The `rake db:test:load` recreates the test database from the current `db/schema.rb`. On subsequent attempts, it is a good idea to first run `db:test:prepare`, as it first checks for pending migrations and warns you appropriately.
-
-NOTE: `db:test:prepare` will fail with an error if `db/schema.rb` doesn't exist.
-
-#### Rake Tasks for Preparing your Application for Testing
-
-| Tasks                          | Description                                                               |
-| ------------------------------ | ------------------------------------------------------------------------- |
-| `rake db:test:clone`           | Recreate the test database from the current environment's database schema |
-| `rake db:test:clone_structure` | Recreate the test database from the development structure                 |
-| `rake db:test:load`            | Recreate the test database from the current `schema.rb`                   |
-| `rake db:test:prepare`         | Check for pending migrations and load the test schema                     |
-| `rake db:test:purge`           | Empty the test database.                                                  |
-
-TIP: You can see all these rake tasks and their descriptions by running `rake --tasks --describe`
 
 ### Running Tests
 

guides/source/upgrading_ruby_on_rails.md

@@ -91,6 +91,13 @@ secrets, you need to:
 
 5. Restart your server.
 
+### Changes to test helper
+
+If your test helper contains a call to
+`ActiveRecord::Migration.check_pending!` this can be removed. The check
+is now done automatically when you `require 'test_help'`, although
+leaving this line in your helper is not harmful in any way.
+
 ### Changes in JSON handling
 
 There are a few major changes related to JSON handling in Rails 4.1.

railties/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   `test_help.rb` now automatically checks/maintains your test datbase
+    schema. (Use `config.active_record.maintain_test_schema = false` to
+    disable.)
+
+    *Jon Leighton*
+
 *   Configure `secrets.yml` and `database.yml` to read configuration
     from the system environment by default for production.
 

railties/lib/rails/generators/rails/app/templates/test/test_helper.rb

@@ -4,8 +4,6 @@ require 'rails/test_help'
 
 class ActiveSupport::TestCase
 <% unless  options[:skip_active_record] -%>
-  ActiveRecord::Migration.check_pending!
-
   # Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
   #
   # Note: You'll currently still have to declare fixtures explicitly in integration tests

railties/lib/rails/test_help.rb

@@ -15,6 +15,8 @@ if ENV["BACKTRACE"].nil?
 end
 
 if defined?(ActiveRecord::Base)
+  ActiveRecord::Migration.maintain_test_schema!
+
   class ActiveSupport::TestCase
     include ActiveRecord::TestFixtures
     self.fixture_path = "#{Rails.root}/test/fixtures/"

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

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)

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