[Django]-How can I unit test django messages?

From django documentation:

Outside of templates, you can use get_messages()

So, you could write something like:

from django.contrib.messages import get_messages

[...]

messages = [m.message for m in get_messages(response.wsgi_request)]
self.assertIn('My message', messages)

This works for me (displays all messages):

print [m.message for m in list(response.context['messages'])]

Also here are a couple of utility methods I have in a test class inherited from Django’s TestCase. If you’d prefer to have them as functions, remove the self arguments and replace self.fail()‘s with a raise.

def assert_message_count(self, response, expect_num):
    """
    Asserts that exactly the given number of messages have been sent.
    """

    actual_num = len(response.context['messages'])
    if actual_num != expect_num:
        self.fail('Message count was %d, expected %d' %
            (actual_num, expect_num))

def assert_message_contains(self, response, text, level=None):
    """
    Asserts that there is exactly one message containing the given text.
    """

    messages = response.context['messages']

    matches = [m for m in messages if text in m.message]

    if len(matches) == 1:
        msg = matches[0]
        if level is not None and msg.level != level:
            self.fail('There was one matching message but with different'
                'level: %s != %s' % (msg.level, level))

        return

    elif len(matches) == 0:
        messages_str = ", ".join('"%s"' % m for m in messages)
        self.fail('No message contained text "%s", messages were: %s' %
            (text, messages_str))
    else:
        self.fail('Multiple messages contained text "%s": %s' %
            (text, ", ".join(('"%s"' % m) for m in matches)))

def assert_message_not_contains(self, response, text):
    """ Assert that no message contains the given text. """

    messages = response.context['messages']

    matches = [m for m in messages if text in m.message]

    if len(matches) > 0:
        self.fail('Message(s) contained text "%s": %s' %
            (text, ", ".join(('"%s"' % m) for m in matches)))

Update

My original answer was written when django was still 1.1 or so. This answer is no longer relevant. See @daveoncode’s answer for a better solution.

Original Answer

I did an experiment to test this. I changed the MESSAGE_STORAGE setting in one of my projects to 'django.contrib.messages.storage.cookie.CookieStorage' and executed a test that I had written to check for messages. It worked.

The key difference from what you were doing is the way I retrieved messages. See below:

def test_message_sending(self):
    data = dict(...)
    response = self.client.post(reverse('my_view'), data)
    messages = self.user.get_and_delete_messages()

    self.assertTrue(messages)
    self.assertEqual('Hey there!', messages[0])

This may be worth a try.

I created a python class to simplify messages testing :

class TestMessageCase(TestCase):
""" class inherited from TestCase to add a function to test messages response """

def assertMessageContains(self, response, messages_list, debug=False):
    """
    Function to test messages returned by the response view

    :param response: The response of the view
    :param messages_list: An ordered list of messages to test
    :type messages_list: list of string
    :param debug: Show all response messages
    :type debug: bool
    """

    response_messages = list(response.context['messages'])

    if debug:
        print(
            " ---------------------------------------------------------------------\n",
            "|              DEBUG MESSAGES RETURNED BY THE RESPONSE              |\n",
            "---------------------------------------------------------------------"
        )
        for i in range(len(response_messages)):
            print(f"Message n°{i + 1} :\n{response_messages[i]}\n\n")
        print(
            " ---------------------------------------------------------------------\n",
            "|                             END DEBUG                             |\n",
            "---------------------------------------------------------------------"
        )

    self.assertEqual(len(response_messages), len(messages_list))
    for i in range(len(response_messages)):
        self.assertEqual(str(response_messages[i]), messages_list[i])

And in test function :

response = self.client.post('/foo/')
self.assertMessageContains(response, ["Foo"])

Simpler version of the stalemate one:

class TestCaseMessagesMixture(object):
    def assertMessageCount(self, response, expect_num):
        """
        Asserts that exactly the given number of messages have been sent.
        """

        actual_num = len(response.context['messages'])
        if actual_num != expect_num:
            self.fail('Message count was %d, expected %d' %
                    (actual_num, expect_num)
                )

    def assertMessageEqual(self, response, text):
        """
        Asserts that the response includes the message text.
        """

        messages = [m.message for m in response.context['messages']]

        if text not in messages:
            self.fail(
                'No message with text "%s", messages were: %s' % 
                    (text, messages)
                )

    def assertMessageNotEqual(self, response, text):
        """
        Asserts that the response does not include the message text.
        """

        messages = [m.message for m in response.context['messages']]

        if text in messages:
            self.fail(
                'Message with text "%s" found, messages were: %s' % 
                    (text, messages)
                )

Test helpers for validation of response messages count and content

def get_response_messages(self, response):
    from django.contrib.messages import get_messages
    return list(get_messages(response.wsgi_request))


def check_response_messages(self, response, message_index=None, message_value=None, exp_count=None):
    messages = self.get_response_messages(response)
    if exp_count is not None:
        self.assertEqual(len(messages), exp_count)

    if message_index is not None:
        message = messages[message_index]
        self.assertIn(message_value, str(message))

Can be used like this

message_value = "You can not switch to another type of account"
self.check_response_messages(response, exp_count=1, message_index=0, message_value=message_value)