2 files changed, 21 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/test_case.rb b/activesupport/lib/active_support/test_case.rb
index fb52fc7083..a7053a1134 100644
--- a/activesupport/lib/active_support/test_case.rb
+++ b/activesupport/lib/active_support/test_case.rb
@@ -6,6 +6,7 @@ require 'active_support/testing/declarative'
 require 'active_support/testing/pending'
 require 'active_support/testing/isolation'
 require 'active_support/core_ext/kernel/reporting'
+require 'active_support/testing/garbage_collection'
 
 begin
   silence_warnings { require 'mocha' }
@@ -37,5 +38,6 @@ module ActiveSupport
     include ActiveSupport::Testing::Deprecation
     include ActiveSupport::Testing::Pending
     extend ActiveSupport::Testing::Declarative
+    include ActiveSupport::Testing::GarbageCollection
   end
 end
diff --git a/activesupport/lib/active_support/testing/garbage_collection.rb b/activesupport/lib/active_support/testing/garbage_collection.rb
new file mode 100644
index 0000000000..7bf9fbafa6
--- /dev/null
+++ b/activesupport/lib/active_support/testing/garbage_collection.rb
@@ -0,0 +1,19 @@
+module ActiveSupport
+  module Testing
+    module GarbageCollection
+      def self.included(base)
+        base.teardown :scrub_leftover_instance_variables
+      end
+
+      private
+
+      RESERVED_INSTANCE_VARIABLES = %w(@test_passed @passed @method_name @__name__ @_result).map(&:to_sym)
+
+      def scrub_leftover_instance_variables
+        (instance_variables.map(&:to_sym) - RESERVED_INSTANCE_VARIABLES).each do |var|
+          remove_instance_variable(var)
+        end
+      end
+    end
+  end
+end