From acb3e8e8a797a1fd321322d27114ef15ff99d440 Mon Sep 17 00:00:00 2001 From: Anton Lodder Date: Thu, 10 Jan 2019 14:12:50 -0500 Subject: [PATCH] Test rewriting assertion when __name__ fails Pytest rewrites assertions so that the items on each side of a comoparison will have easier-to-read names in case of an assertion error. Before doing this, it checks to make sure the object doesn't have a __name__ attribute; however, it uses `hasattr` so if the objects __getattr__ is broken then the test failure message will be the stack trace for this failure instead of a rewritten assertion. --- testing/test_assertrewrite.py | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/testing/test_assertrewrite.py b/testing/test_assertrewrite.py index 4187e365b..840fda2ca 100644 --- a/testing/test_assertrewrite.py +++ b/testing/test_assertrewrite.py @@ -180,6 +180,27 @@ class TestAssertionRewrite(object): assert getmsg(f, {"cls": X}) == "assert cls == 42" + def test_dont_rewrite_if_hasattr_fails(self): + class Y(object): + """ A class whos getattr fails, but not with `AttributeError` """ + + def __getattr__(self, attribute_name): + raise KeyError() + + def __repr__(self): + return "Y" + + def __init__(self): + self.foo = 3 + + def f(): + assert cls().foo == 2 # noqa + + message = getmsg(f, {"cls": Y}) + assert "assert 3 == 2" in message + assert "+ where 3 = Y.foo" in message + assert "+ where Y = cls()" in message + def test_assert_already_has_message(self): def f(): assert False, "something bad!"