Deprecate assertDictContainsSubset()
diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index b02d475..15c7eee 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -934,6 +934,8 @@
 
     def assertDictContainsSubset(self, subset, dictionary, msg=None):
         """Checks whether dictionary is a superset of subset."""
+        warnings.warn('assertDictContainsSubset is deprecated',
+                      DeprecationWarning)
         missing = []
         mismatched = []
         for key, value in subset.items():