diff -r f6199284ef3a Lib/test/test_hmac.py
--- a/Lib/test/test_hmac.py	Wed Mar 14 00:40:57 2012 +0100
+++ b/Lib/test/test_hmac.py	Tue Mar 13 20:35:43 2012 -0700
@@ -248,6 +248,44 @@
         except:
             self.fail("Constructor call with hashlib.sha1 raised exception.")
 
+    def test_withnoncallable_digestmod(self):
+        try:
+            # Use hmac itself as the digestmod since it conforms to PEP 247
+            h = hmac.HMAC(b"key", b"", hmac)
+        except:
+            self.fail("Constructor call with digestmod=hmac raised exception.")
+
+    def test_no_block_size(self):
+        # hmac follows PEP 247 but doesn't have a block_size attribute
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")
+            h = hmac.HMAC(b"key", b"", hmac)
+            assert len(w) == 1
+            assert "No block_size" in str(w[-1].message)
+
+    def test_small_block_size(self):
+        # hmac follows PEP 247 but doesn't have a block_size attribute,
+        # so we need to mock its new() method to fake one for testing.
+        old_new = hmac.new
+        def mock_new(d=""):
+            h = old_new(d)
+            h.block_size = 15
+            return h
+        hmac.new = mock_new
+
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")
+            h = hmac.HMAC(b"key", b"", hmac)
+            assert len(w) == 1
+            assert "block_size of 15 seems too small" in str(w[-1].message)
+
+        hmac.new = old_new
+
+    def test_with_invalid_msg(self):
+        # Constructor call with non-bytes message
+        with self.assertRaises(TypeError):
+            h = hmac.HMAC(u"invalidkey")
+
 class SanityTestCase(unittest.TestCase):
 
     def test_default_is_md5(self):
@@ -256,6 +294,12 @@
         h = hmac.HMAC(b"key")
         self.assertEqual(h.digest_cons, hashlib.md5)
 
+    def test_update_error_handling(self):
+        # Test update method with non-bytes message
+        h = hmac.HMAC(b"key")
+        with self.assertRaises(TypeError):
+            h.update(u"invalidmsg")
+
     def test_exercise_all_methods(self):
         # Exercising all methods once.
         # This must not raise any exceptions