diff --git a/activesupport/test/caching_test.rb b/activesupport/test/caching_test.rb
index 1e3810f6f7f60d938a4352757e8d08f0bc9f4fcc..d4dec81b281b4f9e3450af25c6b4fd37cf6a9787 100644
--- a/activesupport/test/caching_test.rb
+++ b/activesupport/test/caching_test.rb
@@ -140,6 +140,16 @@ def with_env(kv)
 end
 
 class CacheStoreSettingTest < ActiveSupport::TestCase
+  def test_memory_store_gets_created_if_no_arguments_passed_to_lookup_store_method
+    store = ActiveSupport::Cache.lookup_store
+    assert_kind_of(ActiveSupport::Cache::MemoryStore, store)
+  end
+
+  def test_memory_store
+    store = ActiveSupport::Cache.lookup_store :memory_store
+    assert_kind_of(ActiveSupport::Cache::MemoryStore, store)
+  end
+
   def test_file_fragment_cache_store
     store = ActiveSupport::Cache.lookup_store :file_store, "/path/to/cache/directory"
     assert_kind_of(ActiveSupport::Cache::FileStore, store)