diff --git a/guides/source/testing.md b/guides/source/testing.md
index b4c70dfa1dbb5..a324139d1b484 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -221,7 +221,16 @@ Every test contains one or more assertions. Only when all the assertions are suc
 
 ### Maintaining the test database schema
 
-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.
+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. Usually this indicates that your schema is not fully migrated. Running
+the migrations against the development database (`bin/rake db:migrate`) will
+bring the schema up to date.
+
+NOTE: If existing migrations required modifications, the test database needs to
+be rebuilt. This can be done by executing `bin/rake db:test:prepare`.
 
 ### Running Tests