Fixed #10314 -- Added a message prefix argument to Django's test assertions. Thanks to Wes Winham for the original suggestion, and Chistian Oudard for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12273 bcc190cf-cafb-0310-a4f2-bffc1f526a37

AUTHORS

@@ -339,6 +339,7 @@ answer newbie questions, and generally made Django that much better:
     Afonso Fernández Nogueira <fonzzo.django@gmail.com>
     Neal Norwitz <nnorwitz@google.com>
     Todd O'Bryan <toddobryan@mac.com>
+    Christian Oudard <christian.oudard@gmail.com>
     oggie rob <oz.robharvey@gmail.com>
     oggy <ognjen.maric@gmail.com>
     Jay Parlar <parlar@gmail.com>

django/test/testcases.py

@@ -287,34 +287,41 @@ class TransactionTestCase(unittest.TestCase):
             clear_url_caches()
 
     def assertRedirects(self, response, expected_url, status_code=302,
-                        target_status_code=200, host=None):
+                        target_status_code=200, host=None, msg_prefix=''):
         """Asserts that a response redirected to a specific URL, and that the
         redirect URL can be loaded.
 
         Note that assertRedirects won't work for external links since it uses
         TestClient to do a request.
         """
+        if msg_prefix:
+            msg_prefix += ": "
+
         if hasattr(response, 'redirect_chain'):
             # The request was a followed redirect
             self.failUnless(len(response.redirect_chain) > 0,
-                ("Response didn't redirect as expected: Response code was %d"
+                msg_prefix + "Response didn't redirect as expected: Response"
-                " (expected %d)" % (response.status_code, status_code)))
+                " code was %d (expected %d)" %
+                    (response.status_code, status_code))
 
             self.assertEqual(response.redirect_chain[0][1], status_code,
-                ("Initial response didn't redirect as expected: Response code was %d"
+                msg_prefix + "Initial response didn't redirect as expected:"
-                 " (expected %d)" % (response.redirect_chain[0][1], status_code)))
+                " Response code was %d (expected %d)" %
+                    (response.redirect_chain[0][1], status_code))
 
             url, status_code = response.redirect_chain[-1]
 
             self.assertEqual(response.status_code, target_status_code,
-                ("Response didn't redirect as expected: Final Response code was %d"
+                msg_prefix + "Response didn't redirect as expected: Final"
-                " (expected %d)" % (response.status_code, target_status_code)))
+                " Response code was %d (expected %d)" %
+                    (response.status_code, target_status_code))
 
         else:
             # Not a followed redirect
             self.assertEqual(response.status_code, status_code,
-                ("Response didn't redirect as expected: Response code was %d"
+                msg_prefix + "Response didn't redirect as expected: Response"
-                 " (expected %d)" % (response.status_code, status_code)))
+                " code was %d (expected %d)" %
+                    (response.status_code, status_code))
 
             url = response['Location']
             scheme, netloc, path, query, fragment = urlsplit(url)
@@ -324,8 +331,8 @@ class TransactionTestCase(unittest.TestCase):
             # Get the redirection page, using the same client that was used
             # to obtain the original response.
             self.assertEqual(redirect_response.status_code, target_status_code,
-                ("Couldn't retrieve redirection page '%s': response code was %d"
+                msg_prefix + "Couldn't retrieve redirection page '%s':"
-                 " (expected %d)") %
+                " response code was %d (expected %d)" %
                     (path, redirect_response.status_code, target_status_code))
 
         e_scheme, e_netloc, e_path, e_query, e_fragment = urlsplit(expected_url)
@@ -334,10 +341,11 @@ class TransactionTestCase(unittest.TestCase):
                 e_query, e_fragment))
 
         self.assertEqual(url, expected_url,
-            "Response redirected to '%s', expected '%s'" % (url, expected_url))
+            msg_prefix + "Response redirected to '%s', expected '%s'" %
+                (url, expected_url))
 
-
+    def assertContains(self, response, text, count=None, status_code=200,
-    def assertContains(self, response, text, count=None, status_code=200):
+                       msg_prefix=''):
         """
         Asserts that a response indicates that a page was retrieved
         successfully, (i.e., the HTTP status code was as expected), and that
@@ -345,42 +353,52 @@ class TransactionTestCase(unittest.TestCase):
         If ``count`` is None, the count doesn't matter - the assertion is true
         if the text occurs at least once in the response.
         """
+        if msg_prefix:
+            msg_prefix += ": "
+
         self.assertEqual(response.status_code, status_code,
-            "Couldn't retrieve page: Response code was %d (expected %d)'" %
+            msg_prefix + "Couldn't retrieve page: Response code was %d"
-                (response.status_code, status_code))
+            " (expected %d)" % (response.status_code, status_code))
         text = smart_str(text, response._charset)
         real_count = response.content.count(text)
         if count is not None:
             self.assertEqual(real_count, count,
-                "Found %d instances of '%s' in response (expected %d)" %
+                msg_prefix + "Found %d instances of '%s' in response"
-                    (real_count, text, count))
+                " (expected %d)" % (real_count, text, count))
         else:
             self.failUnless(real_count != 0,
-                            "Couldn't find '%s' in response" % text)
+                msg_prefix + "Couldn't find '%s' in response" % text)
 
-    def assertNotContains(self, response, text, status_code=200):
+    def assertNotContains(self, response, text, status_code=200,
+                          msg_prefix=''):
         """
         Asserts that a response indicates that a page was retrieved
         successfully, (i.e., the HTTP status code was as expected), and that
         ``text`` doesn't occurs in the content of the response.
         """
-        self.assertEqual(response.status_code, status_code,
+        if msg_prefix:
-            "Couldn't retrieve page: Response code was %d (expected %d)'" %
+            msg_prefix += ": "
-                (response.status_code, status_code))
-        text = smart_str(text, response._charset)
-        self.assertEqual(response.content.count(text),
-             0, "Response should not contain '%s'" % text)
 
-    def assertFormError(self, response, form, field, errors):
+        self.assertEqual(response.status_code, status_code,
+            msg_prefix + "Couldn't retrieve page: Response code was %d"
+            " (expected %d)" % (response.status_code, status_code))
+        text = smart_str(text, response._charset)
+        self.assertEqual(response.content.count(text), 0,
+            msg_prefix + "Response should not contain '%s'" % text)
+
+    def assertFormError(self, response, form, field, errors, msg_prefix=''):
         """
         Asserts that a form used to render the response has a specific field
         error.
         """
+        if msg_prefix:
+            msg_prefix += ": "
+
         # Put context(s) into a list to simplify processing.
         contexts = to_list(response.context)
         if not contexts:
-            self.fail('Response did not use any contexts to render the'
+            self.fail(msg_prefix + "Response did not use any contexts to"
-                      ' response')
+                      "render the response")
 
         # Put error(s) into a list to simplify processing.
         errors = to_list(errors)
@@ -396,50 +414,57 @@ class TransactionTestCase(unittest.TestCase):
                     if field in context[form].errors:
                         field_errors = context[form].errors[field]
                         self.failUnless(err in field_errors,
-                                        "The field '%s' on form '%s' in"
+                            msg_prefix + "The field '%s' on form '%s' in"
-                                        " context %d does not contain the"
+                            " context %d does not contain the error '%s'"
-                                        " error '%s' (actual errors: %s)" %
+                            " (actual errors: %s)" %
-                                            (field, form, i, err,
+                                (field, form, i, err, repr(field_errors)))
-                                             repr(field_errors)))
                     elif field in context[form].fields:
-                        self.fail("The field '%s' on form '%s' in context %d"
+                        self.fail(msg_prefix + "The field '%s' on form '%s'"
-                                  " contains no errors" % (field, form, i))
+                                  " in context %d contains no errors" %
+                                      (field, form, i))
                     else:
-                        self.fail("The form '%s' in context %d does not"
+                        self.fail(msg_prefix + "The form '%s' in context %d"
-                                  " contain the field '%s'" %
+                                  " does not contain the field '%s'" %
                                       (form, i, field))
                 else:
                     non_field_errors = context[form].non_field_errors()
                     self.failUnless(err in non_field_errors,
-                        "The form '%s' in context %d does not contain the"
+                        msg_prefix + "The form '%s' in context %d does not"
-                        " non-field error '%s' (actual errors: %s)" %
+                        " contain the non-field error '%s'"
+                        " (actual errors: %s)" %
                             (form, i, err, non_field_errors))
         if not found_form:
-            self.fail("The form '%s' was not used to render the response" %
+            self.fail(msg_prefix + "The form '%s' was not used to render the"
-                          form)
+                      " response" % form)
 
-    def assertTemplateUsed(self, response, template_name):
+    def assertTemplateUsed(self, response, template_name, msg_prefix=''):
         """
         Asserts that the template with the provided name was used in rendering
         the response.
         """
+        if msg_prefix:
+            msg_prefix += ": "
+
         template_names = [t.name for t in to_list(response.template)]
         if not template_names:
-            self.fail('No templates used to render the response')
+            self.fail(msg_prefix + "No templates used to render the response")
         self.failUnless(template_name in template_names,
-            (u"Template '%s' was not a template used to render the response."
+            msg_prefix + "Template '%s' was not a template used to render"
-             u" Actual template(s) used: %s") % (template_name,
+            " the response. Actual template(s) used: %s" %
-                                                 u', '.join(template_names)))
+                (template_name, u', '.join(template_names)))
 
-    def assertTemplateNotUsed(self, response, template_name):
+    def assertTemplateNotUsed(self, response, template_name, msg_prefix=''):
         """
         Asserts that the template with the provided name was NOT used in
         rendering the response.
         """
+        if msg_prefix:
+            msg_prefix += ": "
+
         template_names = [t.name for t in to_list(response.template)]
         self.failIf(template_name in template_names,
-            (u"Template '%s' was used unexpectedly in rendering the"
+            msg_prefix + "Template '%s' was used unexpectedly in rendering"
-             u" response") % template_name)
+            " the response" % template_name)
 
 def connections_support_transactions():
     """

docs/topics/testing.txt

@@ -1104,23 +1104,32 @@ Assertions
 
 .. versionadded:: 1.0
 
+.. versionchanged:: 1.2
+    Addded ``msg_prefix`` argument.
+
 As Python's normal ``unittest.TestCase`` class implements assertion methods
 such as ``assertTrue`` and ``assertEquals``, Django's custom ``TestCase`` class
 provides a number of custom assertion methods that are useful for testing Web
 applications:
 
-.. method:: TestCase.assertContains(response, text, count=None, status_code=200)
+The failure messages given by the assertion methods can be customized
+with the ``msg_prefix`` argument. This string will be prefixed to any
+failure message generated by the assertion. This allows you to provide
+additional details that may help you to identify the location and
+cause of an failure in your test suite.
+
+.. method:: TestCase.assertContains(response, text, count=None, status_code=200, msg_prefix='')
 
     Asserts that a ``Response`` instance produced the given ``status_code`` and
     that ``text`` appears in the content of the response. If ``count`` is
     provided, ``text`` must occur exactly ``count`` times in the response.
 
-.. method:: TestCase.assertNotContains(response, text, status_code=200)
+.. method:: TestCase.assertNotContains(response, text, status_code=200, msg_prefix='')
 
     Asserts that a ``Response`` instance produced the given ``status_code`` and
     that ``text`` does not appears in the content of the response.
 
-.. method:: TestCase.assertFormError(response, form, field, errors)
+.. method:: TestCase.assertFormError(response, form, field, errors, msg_prefix='')
 
     Asserts that a field on a form raises the provided list of errors when
     rendered on the form.
@@ -1135,19 +1144,19 @@ applications:
     ``errors`` is an error string, or a list of error strings, that are
     expected as a result of form validation.
 
-.. method:: TestCase.assertTemplateUsed(response, template_name)
+.. method:: TestCase.assertTemplateUsed(response, template_name, msg_prefix='')
 
     Asserts that the template with the given name was used in rendering the
     response.
 
     The name is a string such as ``'admin/index.html'``.
 
-.. method:: TestCase.assertTemplateNotUsed(response, template_name)
+.. method:: TestCase.assertTemplateNotUsed(response, template_name, msg_prefix='')
 
     Asserts that the template with the given name was *not* used in rendering
     the response.
 
-.. method:: TestCase.assertRedirects(response, expected_url, status_code=302, target_status_code=200)
+.. method:: TestCase.assertRedirects(response, expected_url, status_code=302, target_status_code=200, msg_prefix='')
 
     Asserts that the response return a ``status_code`` redirect status, it
     redirected to ``expected_url`` (including any GET data), and the final

tests/regressiontests/test_client_regress/models.py

@@ -31,40 +31,86 @@ class AssertContainsTests(TestCase):
         self.assertContains(response, 'twice')
         self.assertContains(response, 'twice', 2)
 
+        try:
+            self.assertContains(response, 'text', status_code=999)
+        except AssertionError, e:
+            self.assertEquals(str(e), "Couldn't retrieve page: Response code was 200 (expected 999)")
+        try:
+            self.assertContains(response, 'text', status_code=999, msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Couldn't retrieve page: Response code was 200 (expected 999)")
+
+        try:
+            self.assertNotContains(response, 'text', status_code=999)
+        except AssertionError, e:
+            self.assertEquals(str(e), "Couldn't retrieve page: Response code was 200 (expected 999)")
+        try:
+            self.assertNotContains(response, 'text', status_code=999, msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Couldn't retrieve page: Response code was 200 (expected 999)")
+
         try:
             self.assertNotContains(response, 'once')
         except AssertionError, e:
             self.assertEquals(str(e), "Response should not contain 'once'")
+        try:
+            self.assertNotContains(response, 'once', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Response should not contain 'once'")
 
         try:
             self.assertContains(response, 'never', 1)
         except AssertionError, e:
             self.assertEquals(str(e), "Found 0 instances of 'never' in response (expected 1)")
+        try:
+            self.assertContains(response, 'never', 1, msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Found 0 instances of 'never' in response (expected 1)")
 
         try:
             self.assertContains(response, 'once', 0)
         except AssertionError, e:
             self.assertEquals(str(e), "Found 1 instances of 'once' in response (expected 0)")
+        try:
+            self.assertContains(response, 'once', 0, msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Found 1 instances of 'once' in response (expected 0)")
 
         try:
             self.assertContains(response, 'once', 2)
         except AssertionError, e:
             self.assertEquals(str(e), "Found 1 instances of 'once' in response (expected 2)")
+        try:
+            self.assertContains(response, 'once', 2, msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Found 1 instances of 'once' in response (expected 2)")
 
         try:
             self.assertContains(response, 'twice', 1)
         except AssertionError, e:
             self.assertEquals(str(e), "Found 2 instances of 'twice' in response (expected 1)")
+        try:
+            self.assertContains(response, 'twice', 1, msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Found 2 instances of 'twice' in response (expected 1)")
 
         try:
             self.assertContains(response, 'thrice')
         except AssertionError, e:
             self.assertEquals(str(e), "Couldn't find 'thrice' in response")
+        try:
+            self.assertContains(response, 'thrice', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Couldn't find 'thrice' in response")
 
         try:
             self.assertContains(response, 'thrice', 3)
         except AssertionError, e:
             self.assertEquals(str(e), "Found 0 instances of 'thrice' in response (expected 3)")
+        try:
+            self.assertContains(response, 'thrice', 3, msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Found 0 instances of 'thrice' in response (expected 3)")
 
     def test_unicode_contains(self):
         "Unicode characters can be found in template context"
@@ -80,6 +126,7 @@ class AssertContainsTests(TestCase):
         self.assertNotContains(r, u'はたけ')
         self.assertNotContains(r, '\xe3\x81\xaf\xe3\x81\x9f\xe3\x81\x91'.decode('utf-8'))
 
+
 class AssertTemplateUsedTests(TestCase):
     fixtures = ['testdata.json']
 
@@ -95,21 +142,35 @@ class AssertTemplateUsedTests(TestCase):
         except AssertionError, e:
             self.assertEquals(str(e), "No templates used to render the response")
 
+        try:
+            self.assertTemplateUsed(response, 'GET Template', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: No templates used to render the response")
+
     def test_single_context(self):
         "Template assertions work when there is a single context"
         response = self.client.get('/test_client/post_view/', {})
 
-        #
         try:
             self.assertTemplateNotUsed(response, 'Empty GET Template')
         except AssertionError, e:
             self.assertEquals(str(e), "Template 'Empty GET Template' was used unexpectedly in rendering the response")
 
+        try:
+            self.assertTemplateNotUsed(response, 'Empty GET Template', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Template 'Empty GET Template' was used unexpectedly in rendering the response")
+
         try:
             self.assertTemplateUsed(response, 'Empty POST Template')
         except AssertionError, e:
             self.assertEquals(str(e), "Template 'Empty POST Template' was not a template used to render the response. Actual template(s) used: Empty GET Template")
 
+        try:
+            self.assertTemplateUsed(response, 'Empty POST Template', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Template 'Empty POST Template' was not a template used to render the response. Actual template(s) used: Empty GET Template")
+
     def test_multiple_context(self):
         "Template assertions work when there are multiple contexts"
         post_data = {
@@ -146,6 +207,11 @@ class AssertRedirectsTests(TestCase):
         except AssertionError, e:
             self.assertEquals(str(e), "Response didn't redirect as expected: Response code was 301 (expected 302)")
 
+        try:
+            self.assertRedirects(response, '/test_client/get_view/', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Response didn't redirect as expected: Response code was 301 (expected 302)")
+
     def test_lost_query(self):
         "An assertion is raised if the redirect location doesn't preserve GET parameters"
         response = self.client.get('/test_client/redirect_view/', {'var': 'value'})
@@ -154,6 +220,11 @@ class AssertRedirectsTests(TestCase):
         except AssertionError, e:
             self.assertEquals(str(e), "Response redirected to 'http://testserver/test_client/get_view/?var=value', expected 'http://testserver/test_client/get_view/'")
 
+        try:
+            self.assertRedirects(response, '/test_client/get_view/', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Response redirected to 'http://testserver/test_client/get_view/?var=value', expected 'http://testserver/test_client/get_view/'")
+
     def test_incorrect_target(self):
         "An assertion is raised if the response redirects to another target"
         response = self.client.get('/test_client/permanent_redirect_view/')
@@ -172,6 +243,12 @@ class AssertRedirectsTests(TestCase):
         except AssertionError, e:
             self.assertEquals(str(e), "Couldn't retrieve redirection page '/test_client/permanent_redirect_view/': response code was 301 (expected 200)")
 
+        try:
+            # The redirect target responds with a 301 code, not 200
+            self.assertRedirects(response, 'http://testserver/test_client/permanent_redirect_view/', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Couldn't retrieve redirection page '/test_client/permanent_redirect_view/': response code was 301 (expected 200)")
+
     def test_redirect_chain(self):
         "You can follow a redirect chain of multiple redirects"
         response = self.client.get('/test_client_regress/redirects/further/more/', {}, follow=True)
@@ -263,6 +340,11 @@ class AssertRedirectsTests(TestCase):
         except AssertionError, e:
             self.assertEquals(str(e), "Response didn't redirect as expected: Response code was 200 (expected 302)")
 
+        try:
+            self.assertRedirects(response, '/test_client/get_view/', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Response didn't redirect as expected: Response code was 200 (expected 302)")
+
     def test_redirect_on_non_redirect_page(self):
         "An assertion is raised if the original page couldn't be retrieved as expected"
         # This page will redirect with code 301, not 302
@@ -272,6 +354,11 @@ class AssertRedirectsTests(TestCase):
         except AssertionError, e:
             self.assertEquals(str(e), "Response didn't redirect as expected: Response code was 200 (expected 302)")
 
+        try:
+            self.assertRedirects(response, '/test_client/get_view/', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEquals(str(e), "abc: Response didn't redirect as expected: Response code was 200 (expected 302)")
+
 
 class AssertFormErrorTests(TestCase):
     def test_unknown_form(self):
@@ -291,6 +378,10 @@ class AssertFormErrorTests(TestCase):
             self.assertFormError(response, 'wrong_form', 'some_field', 'Some error.')
         except AssertionError, e:
             self.assertEqual(str(e), "The form 'wrong_form' was not used to render the response")
+        try:
+            self.assertFormError(response, 'wrong_form', 'some_field', 'Some error.', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEqual(str(e), "abc: The form 'wrong_form' was not used to render the response")
 
     def test_unknown_field(self):
         "An assertion is raised if the field name is unknown"
@@ -309,6 +400,10 @@ class AssertFormErrorTests(TestCase):
             self.assertFormError(response, 'form', 'some_field', 'Some error.')
         except AssertionError, e:
             self.assertEqual(str(e), "The form 'form' in context 0 does not contain the field 'some_field'")
+        try:
+            self.assertFormError(response, 'form', 'some_field', 'Some error.', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEqual(str(e), "abc: The form 'form' in context 0 does not contain the field 'some_field'")
 
     def test_noerror_field(self):
         "An assertion is raised if the field doesn't have any errors"
@@ -327,6 +422,10 @@ class AssertFormErrorTests(TestCase):
             self.assertFormError(response, 'form', 'value', 'Some error.')
         except AssertionError, e:
             self.assertEqual(str(e), "The field 'value' on form 'form' in context 0 contains no errors")
+        try:
+            self.assertFormError(response, 'form', 'value', 'Some error.', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEqual(str(e), "abc: The field 'value' on form 'form' in context 0 contains no errors")
 
     def test_unknown_error(self):
         "An assertion is raised if the field doesn't contain the provided error"
@@ -345,6 +444,10 @@ class AssertFormErrorTests(TestCase):
             self.assertFormError(response, 'form', 'email', 'Some error.')
         except AssertionError, e:
             self.assertEqual(str(e), "The field 'email' on form 'form' in context 0 does not contain the error 'Some error.' (actual errors: [u'Enter a valid e-mail address.'])")
+        try:
+            self.assertFormError(response, 'form', 'email', 'Some error.', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEqual(str(e), "abc: The field 'email' on form 'form' in context 0 does not contain the error 'Some error.' (actual errors: [u'Enter a valid e-mail address.'])")
 
     def test_unknown_nonfield_error(self):
         """
@@ -366,6 +469,10 @@ class AssertFormErrorTests(TestCase):
             self.assertFormError(response, 'form', None, 'Some error.')
         except AssertionError, e:
             self.assertEqual(str(e), "The form 'form' in context 0 does not contain the non-field error 'Some error.' (actual errors: )")
+        try:
+            self.assertFormError(response, 'form', None, 'Some error.', msg_prefix='abc')
+        except AssertionError, e:
+            self.assertEqual(str(e), "abc: The form 'form' in context 0 does not contain the non-field error 'Some error.' (actual errors: )")
 
 class LoginTests(TestCase):
     fixtures = ['testdata']