Python how to assert that a method has been called

Question

I have the following test case in python.

class RulesTest(TestCase):

    request_length = 484
    url = "http://www.ndtv.com"

    def setUp(self):
        har_data = open('/Users/rokumar/SiteAnalysisGit/Src/hct/hct/test.har')
        self.data = json.load(har_data)
        self.rule = models.Rule(name=RULES.DNS,user=None,
            threshold=None)
        self.rule.save()

    def tearDown(self):
        self.rule.delete()

    def test_parse_har(self):
        with patch.object(rules, 'add_dns_analysis', return_value=None) as \
           dns_mock: 
            dns_mock.add_dns_analysis('test result', 'test url')
            result = rules.parse_har(self.data,[self.rule],RulesTest.url)
            self.assertEqual(result[RULES.TOTAL_REQUESTS], 484)
            self.assertEqual(result[RULES.HTML_SIZE], 241592)
            self.assertEqual(result[RULES.JS_SIZE], 1006469)
            dns_mock.assert_called_once_with('test result', 'test url')

The last assertion fails telling that the actual call got made. Why is python not bypassing this call.

Answer 1

Maybe you want to check if the method add_dns_analysis was call by parse_har() :

Rewrite your test as

def test_parse_har(self):
    with patch.object(rules, 'add_dns_analysis', return_value=None) as \
       dns_mock: 
        result = rules.parse_har(self.data,[self.rule],RulesTest.url)
        self.assertEqual(result[RULES.TOTAL_REQUESTS], 484)
        self.assertEqual(result[RULES.HTML_SIZE], 241592)
        self.assertEqual(result[RULES.JS_SIZE], 1006469)
        dns_mock.assert_called_once_with('test result', 'test url')