test_named_temporary_file.py

class TestNamedTemporaryFile(TestCase):

    def setUp(self):
        # set up the mock
        # you could use ByteTestCase when you are at byte.nl ;)
        mockobj = mock.Mock()
        patcher = mock.patch("tempfile.NamedTemporaryFile", mockobj)
        self.addCleanup(patcher.stop)
        patcher.start()

        def enter(*args):
            return self.mock_tempfile

        def exit(*args):
            pass

        # set exit and enter on mocked instance
        self.mock_tempfile = mockobj.return_value
        self.mock_tempfile.__exit__ = exit
        self.mock_tempfile.__enter__ = enter
        self.mock_tempfile.name = "/tmp/mytempfile"