Merge branch 'backstage/gb/migrations-tests-schema-version' into backstage/gb/migrate-stages-statuses

* backstage/gb/migrations-tests-schema-version:
  Migrate down before each migration unit test
  Disable db_cleaner tables caching in migrations tests
  Extend migrations testing documentation
  Make it possible to provide schema version in tests
  Migrate db schema for context in :migration specs

1 files changed, 8 insertions, 2 deletions

diff --git a/spec/migrations/README.md b/spec/migrations/README.md
index 05d4f35db72..45cf25b96de 100644
--- a/spec/migrations/README.md
+++ b/spec/migrations/README.md
@@ -28,6 +28,14 @@ The `after` hook will migrate the database **up** and reinstitutes the latest
 schema version, so that the process does not affect subsequent specs and
 ensures proper isolation.
 
+## Testing a class that is not an ActiveRecord::Migration
+
+In order to test a class that is not a migration itself, you will need to
+manually provide a required schema version. Please add a `schema` tag to a
+context that you want to switch the database schema within.
+
+Example: `describe SomeClass, :migration, schema: 20170608152748`.
+
 ## Available helpers
 
 Use `table` helper to create a temporary `ActiveRecord::Base` derived model
@@ -80,8 +88,6 @@ end
 
 ## Best practices
 
-1. Use only one test example per migration unless there is a good reason to
-use more.
 1. Note that this type of tests do not run within the transaction, we use
 a truncation database cleanup strategy. Do not depend on transaction being
 present.