from testfixtures.mock import Mock, call from testfixtures import Replacer, compare from testfixtures.components import TestComponents from unittest import TestCase from warnings import catch_warnings class ComponentsTests(TestCase): def test_atexit(self): m = Mock() with Replacer() as r: r.replace('atexit.register', m.register) c = TestComponents() expected = [call.register(c.atexit)] compare(expected, m.mock_calls) with catch_warnings(record=True) as w: c.atexit() self.assertTrue(len(w), 1) compare(str(w[0].message), ( # pragma: no branch "TestComponents instances not uninstalled by shutdown!" )) c.uninstall() compare(expected, m.mock_calls) # check re-running has no ill effects c.atexit() compare(expected, m.mock_calls)