diff --git a/tests/util.py b/tests/util.py
index 2cab91f..7520a28 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -305,10 +305,26 @@
         :param constructionArgs: Positional arguments to use with
             :py:data:`theType` to create an instance of it.
         """
-        self.assertEqual(theType.__name__, name)
-        self.assertTrue(isinstance(theType, type))
-        instance = theType(*constructionArgs)
-        self.assertIdentical(type(instance), theType)
+        assert is_consistent_type(theType, name, *constructionArgs)
+
+
+def is_consistent_type(theType, name, *constructionArgs):
+    """
+    Perform various assertions about *theType* to ensure that it is a
+    well-defined type.  This is useful for extension types, where it's
+    pretty easy to do something wacky.  If something about the type is
+    unusual, an exception will be raised.
+
+    :param theType: The type object about which to make assertions.
+    :param name: A string giving the name of the type.
+    :param constructionArgs: Positional arguments to use with
+        *theType* to create an instance of it.
+    """
+    assert theType.__name__ == name
+    assert isinstance(theType, type)
+    instance = theType(*constructionArgs)
+    assert type(instance) is theType
+    return True
 
 
 class EqualityTestsMixin(object):