1 files changed, 36 insertions, 0 deletions
diff --git a/Lib/test/test_email/test_parser.py b/Lib/test/test_email/test_parser.py
new file mode 100644
index 00000000000..3abd11a45c0
--- /dev/null
+++ b/Lib/test/test_email/test_parser.py
@@ -0,0 +1,36 @@
+import io
+import email
+import unittest
+from email.message import Message
+from test.test_email import TestEmailBase
+
+
+class TestCustomMessage(TestEmailBase):
+
+    class MyMessage(Message):
+        def __init__(self, policy):
+            self.check_policy = policy
+            super().__init__()
+
+    MyPolicy = TestEmailBase.policy.clone(linesep='boo')
+
+    def test_custom_message_gets_policy_if_possible_from_string(self):
+        msg = email.message_from_string("Subject: bogus\n\nmsg\n",
+                                        self.MyMessage,
+                                        policy=self.MyPolicy)
+        self.assertTrue(isinstance(msg, self.MyMessage))
+        self.assertIs(msg.check_policy, self.MyPolicy)
+
+    def test_custom_message_gets_policy_if_possible_from_file(self):
+        source_file = io.StringIO("Subject: bogus\n\nmsg\n")
+        msg = email.message_from_file(source_file,
+                                      self.MyMessage,
+                                      policy=self.MyPolicy)
+        self.assertTrue(isinstance(msg, self.MyMessage))
+        self.assertIs(msg.check_policy, self.MyPolicy)
+
+    # XXX add tests for other functions that take Message arg.
+
+
+if __name__ == '__main__':
+    unittest.main()