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".

3 files changed, 60 insertions, 1 deletions

diff --git a/activerecord/test/cases/fixtures_test.rb b/activerecord/test/cases/fixtures_test.rb
index a7f01e898e..7ad032a632 100644
--- a/activerecord/test/cases/fixtures_test.rb
+++ b/activerecord/test/cases/fixtures_test.rb
@@ -1279,6 +1279,33 @@ class CustomNameForFixtureOrModelTest < ActiveRecord::TestCase
   end
 end
 
+class IgnoreFixturesTest < ActiveRecord::TestCase
+  fixtures :other_books, :parrots
+
+  test "ignores books fixtures" do
+    assert_raise(StandardError) { other_books(:published) }
+    assert_raise(StandardError) { other_books(:published_paperback) }
+    assert_raise(StandardError) { other_books(:published_ebook) }
+
+    assert_equal 2, Book.count
+    assert_equal "Agile Web Development with Rails", other_books(:awdr).name
+    assert_equal "published", other_books(:awdr).status
+    assert_equal "paperback", other_books(:awdr).format
+    assert_equal "english", other_books(:awdr).language
+
+    assert_equal "Ruby for Rails", other_books(:rfr).name
+    assert_equal "ebook", other_books(:rfr).format
+    assert_equal "published", other_books(:rfr).status
+  end
+
+  test "ignores parrots fixtures" do
+    assert_raise(StandardError) { parrots(:DEFAULT) }
+    assert_raise(StandardError) { parrots(:DEAD_PARROT) }
+
+    assert_equal "DeadParrot", parrots(:polly).parrot_sti_class
+  end
+end
+
 class FixturesWithDefaultScopeTest < ActiveRecord::TestCase
   fixtures :bulbs
 
diff --git a/activerecord/test/fixtures/other_books.yml b/activerecord/test/fixtures/other_books.yml
new file mode 100644
index 0000000000..62806c03d7
--- /dev/null
+++ b/activerecord/test/fixtures/other_books.yml
@@ -0,0 +1,26 @@
+_fixture:
+  model_class: Book
+  ignore:
+    - PUBLISHED
+    - PUBLISHED_PAPERBACK
+    - PUBLISHED_EBOOK
+
+PUBLISHED: &PUBLISHED
+  status: :published
+
+PUBLISHED_PAPERBACK: &PUBLISHED_PAPERBACK
+  <<: *PUBLISHED
+  format: "paperback"
+  language: :english
+
+PUBLISHED_EBOOK: &PUBLISHED_EBOOK
+  <<: *PUBLISHED
+  format: "ebook"
+
+awdr:
+  <<: *PUBLISHED_PAPERBACK
+  name: "Agile Web Development with Rails"
+
+rfr:
+  <<: *PUBLISHED_EBOOK
+  name: "Ruby for Rails"
diff --git a/activerecord/test/fixtures/parrots.yml b/activerecord/test/fixtures/parrots.yml
index 8425ef98e0..4f0a090e03 100644
--- a/activerecord/test/fixtures/parrots.yml
+++ b/activerecord/test/fixtures/parrots.yml
@@ -1,3 +1,9 @@
+_fixture:
+  ignore: DEAD_PARROT
+
+DEAD_PARROT: &DEAD_PARROT
+  parrot_sti_class: DeadParrot
+
 george:
   name: "Curious George"
   treasures: diamond, sapphire
@@ -17,7 +23,7 @@ polly:
   name: $LABEL
   killer: blackbeard
   treasures: sapphire, ruby
-  parrot_sti_class: DeadParrot
+  <<: *DEAD_PARROT
 
 DEFAULTS: &DEFAULTS
   treasures: sapphire, ruby