1 files changed, 103 insertions, 0 deletions
diff --git a/activerecord/test/cases/migration/references_index_test.rb b/activerecord/test/cases/migration/references_index_test.rb
new file mode 100644
index 0000000000..e41377d817
--- /dev/null
+++ b/activerecord/test/cases/migration/references_index_test.rb
@@ -0,0 +1,103 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+
+module ActiveRecord
+  class Migration
+    class ReferencesIndexTest < ActiveRecord::TestCase
+      attr_reader :connection, :table_name
+
+      def setup
+        super
+        @connection = ActiveRecord::Base.connection
+        @table_name = :testings
+      end
+
+      teardown do
+        connection.drop_table :testings rescue nil
+      end
+
+      def test_creates_index
+        connection.create_table table_name do |t|
+          t.references :foo, index: true
+        end
+
+        assert connection.index_exists?(table_name, :foo_id, name: :index_testings_on_foo_id)
+      end
+
+      def test_creates_index_by_default_even_if_index_option_is_not_passed
+        connection.create_table table_name do |t|
+          t.references :foo
+        end
+
+        assert connection.index_exists?(table_name, :foo_id, name: :index_testings_on_foo_id)
+      end
+
+      def test_does_not_create_index_explicit
+        connection.create_table table_name do |t|
+          t.references :foo, index: false
+        end
+
+        assert_not connection.index_exists?(table_name, :foo_id, name: :index_testings_on_foo_id)
+      end
+
+      def test_creates_index_with_options
+        connection.create_table table_name do |t|
+          t.references :foo, index: { name: :index_testings_on_yo_momma }
+          t.references :bar, index: { unique: true }
+        end
+
+        assert connection.index_exists?(table_name, :foo_id, name: :index_testings_on_yo_momma)
+        assert connection.index_exists?(table_name, :bar_id, name: :index_testings_on_bar_id, unique: true)
+      end
+
+      unless current_adapter? :OracleAdapter
+        def test_creates_polymorphic_index
+          connection.create_table table_name do |t|
+            t.references :foo, polymorphic: true, index: true
+          end
+
+          assert connection.index_exists?(table_name, [:foo_type, :foo_id], name: :index_testings_on_foo_type_and_foo_id)
+        end
+      end
+
+      def test_creates_index_for_existing_table
+        connection.create_table table_name
+        connection.change_table table_name do |t|
+          t.references :foo, index: true
+        end
+
+        assert connection.index_exists?(table_name, :foo_id, name: :index_testings_on_foo_id)
+      end
+
+      def test_creates_index_for_existing_table_even_if_index_option_is_not_passed
+        connection.create_table table_name
+        connection.change_table table_name do |t|
+          t.references :foo
+        end
+
+        assert connection.index_exists?(table_name, :foo_id, name: :index_testings_on_foo_id)
+      end
+
+      def test_does_not_create_index_for_existing_table_explicit
+        connection.create_table table_name
+        connection.change_table table_name do |t|
+          t.references :foo, index: false
+        end
+
+        assert_not connection.index_exists?(table_name, :foo_id, name: :index_testings_on_foo_id)
+      end
+
+      unless current_adapter? :OracleAdapter
+        def test_creates_polymorphic_index_for_existing_table
+          connection.create_table table_name
+          connection.change_table table_name do |t|
+            t.references :foo, polymorphic: true, index: true
+          end
+
+          assert connection.index_exists?(table_name, [:foo_type, :foo_id], name: :index_testings_on_foo_type_and_foo_id)
+        end
+      end
+    end
+  end
+end