MockMemcacheClient.cas: don't set the value if the key doesn't exist

Author: snarfed

pymemcache/test/test_client.py

@@ -1592,6 +1592,9 @@ def test_cas_not_found(self):
         result = client.cas(b"key", b"value", b"123", noreply=False)
         assert result is None
 
+        result = client.get(b"key")
+        assert result is None
+
 
 class TestPrefixedClient(ClientTestMixin, unittest.TestCase):
     def make_client(self, mock_socket_values, **kwargs):

pymemcache/test/utils.py

@@ -235,7 +235,6 @@ def cas(self, key, value, cas_token, expire=0, noreply=False, **kwargs):
         key = self.check_key(key)
 
         if key not in self._contents:
-            self.set(key, value, noreply=noreply, **kwargs)
             return True if noreply else None
 
         elif self._cas_ids.get(key) != cas_token: