2 files changed, 52 insertions, 0 deletions
diff --git a/activerecord/test/cases/migration/compatibility_test.rb b/activerecord/test/cases/migration/compatibility_test.rb
new file mode 100644
index 0000000000..267d2fcccc
--- /dev/null
+++ b/activerecord/test/cases/migration/compatibility_test.rb
@@ -0,0 +1,42 @@
+require 'cases/helper'
+
+module ActiveRecord
+  class Migration
+    class CompatibilityTest < ActiveRecord::TestCase
+      attr_reader :connection
+      self.use_transactional_tests = false
+
+      def setup
+        super
+        @connection = ActiveRecord::Base.connection
+        @verbose_was = ActiveRecord::Migration.verbose
+        ActiveRecord::Migration.verbose = false
+
+        connection.create_table :testings do |t|
+          t.column :foo, :string, :limit => 100
+          t.column :bar, :string, :limit => 100
+        end
+      end
+
+      teardown do
+        connection.drop_table :testings rescue nil
+        ActiveRecord::Migration.verbose = @verbose_was
+      end
+
+      def test_migration_doesnt_remove_named_index
+        connection.add_index :testings, :foo, :name => "custom_index_name"
+
+        migration = Class.new(ActiveRecord::Migration[4.2]) {
+          def version; 101 end
+          def migrate(x)
+            remove_index :testings, :foo
+          end
+        }.new
+
+        assert connection.index_exists?(:testings, :foo, name: "custom_index_name")
+        assert_raise(StandardError) { ActiveRecord::Migrator.new(:up, [migration]).migrate }
+        assert connection.index_exists?(:testings, :foo, name: "custom_index_name")
+      end
+    end
+  end
+end
diff --git a/activerecord/test/cases/migration/index_test.rb b/activerecord/test/cases/migration/index_test.rb
index 33ff0ee73d..5abd37bfa2 100644
--- a/activerecord/test/cases/migration/index_test.rb
+++ b/activerecord/test/cases/migration/index_test.rb
@@ -130,7 +130,17 @@ module ActiveRecord
       def test_named_index_exists
         connection.add_index :testings, :foo, :name => "custom_index_name"
 
+        assert connection.index_exists?(:testings, :foo)
         assert connection.index_exists?(:testings, :foo, :name => "custom_index_name")
+        assert !connection.index_exists?(:testings, :foo, :name => "other_index_name")
+      end
+
+      def test_remove_named_index
+        connection.add_index :testings, :foo, :name => "custom_index_name"
+
+        assert connection.index_exists?(:testings, :foo)
+        connection.remove_index :testings, :foo
+        assert !connection.index_exists?(:testings, :foo)
       end
 
       def test_add_index_attribute_length_limit