Allow specify fixtures to be ignored

Allow specifying what fixtures can be ignored by setting
`ignore` in fixtures YAML file:

    # users.yml
    _fixture:
      ignore:
        - base

    base: &base
      admin: false
      introduction: "This is a default description"

    admin:
      <<: *base
      admin: true

    visitor:
      <<: *base

In the above example, "base" fixture will be ignored when creating
users fixture. This is helpful when you want to inherit attributes
and it makes your fixtures more "DRY".

1 files changed, 4 insertions, 0 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 366032c734..7f2071189b 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Allow specifying fixtures to be ignored by setting `ignore` in YAML file's '_fixture' section.
+
+    *Tongfei Gao*
+
 *   Make the DATABASE_URL env variable only affect the primary connection. Add new env variables for multiple databases.
 
     *John Crepezzi*, *Eileen Uchitelle*