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".

1 files changed, 7 insertions, 0 deletions

diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 2f0f3573fb..bca1d36ab7 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/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.