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".

6 files changed, 86 insertions, 28 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index e60925827b..e874486b53 100644
--- a/activerecord/CHANGELOG.md
+++ b/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
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 8808ad5a4c..18ee77f6fe 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/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.")
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 7d7e97e6c9..fc84b907a5 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/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
diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 2a8cd83285..ec85b3c843 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/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
diff --git a/activerecord/lib/active_record/railties/databases.rake b/activerecord/lib/active_record/railties/databases.rake
index 4b769aa11c..25d42bbf2d 100644
--- a/activerecord/lib/active_record/railties/databases.rake
+++ b/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.check_schema_file(file)
-      load(file)
+      ActiveRecord::Tasks::DatabaseTasks.load_schema(:ruby, ENV['SCHEMA'])
     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.check_schema_file(filename)
-      current_config = ActiveRecord::Tasks::DatabaseTasks.current_config
-      ActiveRecord::Tasks::DatabaseTasks.structure_load(current_config, filename)
+      ActiveRecord::Tasks::DatabaseTasks.load_schema(:sql, ENV['DB_STRUCTURE'])
     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']
diff --git a/activerecord/lib/active_record/tasks/database_tasks.rb b/activerecord/lib/active_record/tasks/database_tasks.rb
index acb7c65af5..afd493011e 100644
--- a/activerecord/lib/active_record/tasks/database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/database_tasks.rb
@@ -36,9 +36,8 @@ module ActiveRecord
     module DatabaseTasks
       extend self
 
-      attr_writer :current_config
-      attr_accessor :database_configuration, :migrations_paths, :seed_loader, :db_dir,
-                    :fixtures_path, :env, :root
+      attr_writer :current_config, :db_dir, :migrations_paths, :fixtures_path, :root, :env, :seed_loader
+      attr_accessor :database_configuration
 
       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.}