Prefer assertRaisesMessage over assertRaises

tests/admin_utils/tests.py

@@ -222,7 +222,7 @@ def test_label_for_field(self):
             "article"
         )
 
-        with self.assertRaises(AttributeError):
+        with self.assertRaisesMessage(AttributeError, "Unable to lookup 'unknown' on Article"):
             label_for_field("unknown", Article)
 
         def test_callable(obj):

tests/aggregation_regress/tests.py

@@ -430,13 +430,23 @@ def test_decimal_aggregate_annotation_filter(self):
 
     def test_field_error(self):
         # Bad field requests in aggregates are caught and reported
-        with self.assertRaises(FieldError):
+        msg = (
+            "Cannot resolve keyword 'foo' into field. Choices are: authors, "
+            "contact, contact_id, hardbackbook, id, isbn, name, pages, price, "
+            "pubdate, publisher, publisher_id, rating, store, tags"
+        )
+        with self.assertRaisesMessage(FieldError, msg):
             Book.objects.all().aggregate(num_authors=Count('foo'))
 
-        with self.assertRaises(FieldError):
+        with self.assertRaisesMessage(FieldError, msg):
             Book.objects.all().annotate(num_authors=Count('foo'))
 
-        with self.assertRaises(FieldError):
+        msg = (
+            "Cannot resolve keyword 'foo' into field. Choices are: authors, "
+            "contact, contact_id, hardbackbook, id, isbn, name, num_authors, "
+            "pages, price, pubdate, publisher, publisher_id, rating, store, tags"
+        )
+        with self.assertRaisesMessage(FieldError, msg):
             Book.objects.all().annotate(num_authors=Count('authors__id')).aggregate(Max('foo'))
 
     def test_more(self):
@@ -737,19 +747,22 @@ def test_more_more(self):
 
     def test_duplicate_alias(self):
         # Regression for #11256 - duplicating a default alias raises ValueError.
-        with self.assertRaises(ValueError):
+        msg = "The named annotation 'authors__age__avg' conflicts with the default name for another annotation."
+        with self.assertRaisesMessage(ValueError, msg):
             Book.objects.all().annotate(Avg('authors__age'), authors__age__avg=Avg('authors__age'))
 
     def test_field_name_conflict(self):
         # Regression for #11256 - providing an aggregate name
         # that conflicts with a field name on the model raises ValueError
-        with self.assertRaises(ValueError):
+        msg = "The annotation 'age' conflicts with a field on the model."
+        with self.assertRaisesMessage(ValueError, msg):
             Author.objects.annotate(age=Avg('friends__age'))
 
     def test_m2m_name_conflict(self):
         # Regression for #11256 - providing an aggregate name
         # that conflicts with an m2m name on the model raises ValueError
-        with self.assertRaises(ValueError):
+        msg = "The annotation 'friends' conflicts with a field on the model."
+        with self.assertRaisesMessage(ValueError, msg):
             Author.objects.annotate(friends=Count('friends'))
 
     def test_values_queryset_non_conflict(self):
@@ -777,7 +790,8 @@ def test_values_queryset_non_conflict(self):
     def test_reverse_relation_name_conflict(self):
         # Regression for #11256 - providing an aggregate name
         # that conflicts with a reverse-related name on the model raises ValueError
-        with self.assertRaises(ValueError):
+        msg = "The annotation 'book_contact_set' conflicts with a field on the model."
+        with self.assertRaisesMessage(ValueError, msg):
             Author.objects.annotate(book_contact_set=Avg('friends__age'))
 
     def test_pickle(self):
@@ -936,7 +950,8 @@ def test_more_more_more(self):
 
         # Regression for #10766 - Shouldn't be able to reference an aggregate
         # fields in an aggregate() call.
-        with self.assertRaises(FieldError):
+        msg = "Cannot compute Avg('mean_age'): 'mean_age' is an aggregate"
+        with self.assertRaisesMessage(FieldError, msg):
             Book.objects.annotate(mean_age=Avg('authors__age')).annotate(Avg('mean_age'))
 
     def test_empty_filter_count(self):

tests/basic/tests.py

@@ -397,7 +397,7 @@ def test_eq(self):
     def test_hash(self):
         # Value based on PK
         self.assertEqual(hash(Article(id=1)), hash(1))
-        with self.assertRaises(TypeError):
+        with self.assertRaisesMessage(TypeError, 'Model instances without primary key value are unhashable'):
             # No PK value -> unhashable (because save() would then change
             # hash)
             hash(Article())
@@ -688,7 +688,8 @@ def test_refresh(self):
 
     def test_unknown_kwarg(self):
         s = SelfRef.objects.create()
-        with self.assertRaises(TypeError):
+        msg = "refresh_from_db() got an unexpected keyword argument 'unknown_kwarg'"
+        with self.assertRaisesMessage(TypeError, msg):
             s.refresh_from_db(unknown_kwarg=10)
 
     def test_refresh_fk(self):

tests/custom_columns/tests.py

@@ -37,7 +37,11 @@ def test_filter_first_name(self):
         )
 
     def test_field_error(self):
-        with self.assertRaises(FieldError):
+        msg = (
+            "Cannot resolve keyword 'firstname' into field. Choices are: "
+            "Author_ID, article, first_name, last_name, primary_set"
+        )
+        with self.assertRaisesMessage(FieldError, msg):
             Author.objects.filter(firstname__exact="John")
 
     def test_attribute_error(self):

tests/custom_lookups/tests.py

@@ -501,13 +501,14 @@ class LookupTransformCallOrderTests(TestCase):
     def test_call_order(self):
         with register_lookup(models.DateField, TrackCallsYearTransform):
             # junk lookup - tries lookup, then transform, then fails
-            with self.assertRaises(FieldError):
+            msg = "Unsupported lookup 'junk' for IntegerField or join on the field not permitted."
+            with self.assertRaisesMessage(FieldError, msg):
                 Author.objects.filter(birthdate__testyear__junk=2012)
             self.assertEqual(TrackCallsYearTransform.call_order,
                              ['lookup', 'transform'])
             TrackCallsYearTransform.call_order = []
             # junk transform - tries transform only, then fails
-            with self.assertRaises(FieldError):
+            with self.assertRaisesMessage(FieldError, msg):
                 Author.objects.filter(birthdate__testyear__junk__more_junk=2012)
             self.assertEqual(TrackCallsYearTransform.call_order,
                              ['transform'])

tests/custom_managers/tests.py

@@ -47,7 +47,8 @@ def test_queryset_copied_to_default(self):
             # Public methods are copied
             manager.public_method()
             # Private methods are not copied
-            with self.assertRaises(AttributeError):
+            msg = "%r object has no attribute '_private_method'" % manager.__class__.__name__
+            with self.assertRaisesMessage(AttributeError, msg):
                 manager._private_method()
 
     def test_manager_honors_queryset_only(self):
@@ -56,7 +57,8 @@ def test_manager_honors_queryset_only(self):
             # Methods with queryset_only=False are copied even if they are private.
             manager._optin_private_method()
             # Methods with queryset_only=True aren't copied even if they are public.
-            with self.assertRaises(AttributeError):
+            msg = "%r object has no attribute 'optout_public_method'" % manager.__class__.__name__
+            with self.assertRaisesMessage(AttributeError, msg):
                 manager.optout_public_method()
 
     def test_manager_use_queryset_methods(self):
@@ -90,7 +92,7 @@ def test_manager_attributes(self):
         querysets.
         """
         Person.custom_queryset_custom_manager.manager_only()
-        with self.assertRaises(AttributeError):
+        with self.assertRaisesMessage(AttributeError, "'CustomQuerySet' object has no attribute 'manager_only'"):
             Person.custom_queryset_custom_manager.all().manager_only()
 
     def test_queryset_and_manager(self):
@@ -113,7 +115,7 @@ def test_no_objects(self):
         The default manager, "objects", doesn't exist, because a custom one
         was provided.
         """
-        with self.assertRaises(AttributeError):
+        with self.assertRaisesMessage(AttributeError, "type object 'Book' has no attribute 'objects'"):
             Book.objects
 
     def test_filtering(self):

tests/custom_pk/tests.py

@@ -145,7 +145,7 @@ def test_pk_attributes(self):
         # Or we can use the real attribute name for the primary key:
         self.assertEqual(e.employee_code, 123)
 
-        with self.assertRaises(AttributeError):
+        with self.assertRaisesMessage(AttributeError, "'Employee' object has no attribute 'id'"):
             e.id
 
     def test_in_bulk(self):

tests/distinct_on_fields/tests.py

@@ -97,16 +97,18 @@ def test_basic_distinct_on(self):
 
     def test_distinct_not_implemented_checks(self):
         # distinct + annotate not allowed
-        with self.assertRaises(NotImplementedError):
+        msg = 'annotate() + distinct(fields) is not implemented.'
+        with self.assertRaisesMessage(NotImplementedError, msg):
             Celebrity.objects.annotate(Max('id')).distinct('id')[0]
-        with self.assertRaises(NotImplementedError):
+        with self.assertRaisesMessage(NotImplementedError, msg):
             Celebrity.objects.distinct('id').annotate(Max('id'))[0]
 
         # However this check is done only when the query executes, so you
         # can use distinct() to remove the fields before execution.
         Celebrity.objects.distinct('id').annotate(Max('id')).distinct()[0]
         # distinct + aggregate not allowed
-        with self.assertRaises(NotImplementedError):
+        msg = 'aggregate() + distinct(fields) not implemented.'
+        with self.assertRaisesMessage(NotImplementedError, msg):
             Celebrity.objects.distinct('id').aggregate(Max('id'))
 
     def test_distinct_on_in_ordered_subquery(self):

tests/expressions/tests.py

@@ -247,7 +247,8 @@ def test_filter_with_join(self):
         )
 
         with transaction.atomic():
-            with self.assertRaises(FieldError):
+            msg = "Joined field references are not permitted in this query"
+            with self.assertRaisesMessage(FieldError, msg):
                 Company.objects.exclude(
                     ceo__firstname=F('point_of_contact__firstname')
                 ).update(name=F('point_of_contact__lastname'))
@@ -281,7 +282,8 @@ def test_new_object_create(self):
 
     def test_object_create_with_aggregate(self):
         # Aggregates are not allowed when inserting new data
-        with self.assertRaisesMessage(FieldError, 'Aggregate functions are not allowed in this query'):
+        msg = 'Aggregate functions are not allowed in this query'
+        with self.assertRaisesMessage(FieldError, msg):
             Company.objects.create(
                 name='Company', num_employees=Max(Value(1)), num_chairs=1,
                 ceo=Employee.objects.create(firstname="Just", lastname="Doit", salary=30),
@@ -300,7 +302,8 @@ def test():
         test_gmbh.point_of_contact = test_gmbh.ceo
         test_gmbh.save()
         test_gmbh.name = F("ceo__last_name")
-        with self.assertRaises(FieldError):
+        msg = 'Joined field references are not permitted in this query'
+        with self.assertRaisesMessage(FieldError, msg):
             test_gmbh.save()
 
     def test_object_update_unsaved_objects(self):

tests/flatpages_tests/test_templatetags.py

@@ -128,17 +128,21 @@ def test_parsing_errors(self):
         def render(t):
             return Template(t).render(Context())
 
-        with self.assertRaises(TemplateSyntaxError):
+        msg = (
+            "get_flatpages expects a syntax of get_flatpages "
+            "['url_starts_with'] [for user] as context_name"
+        )
+        with self.assertRaisesMessage(TemplateSyntaxError, msg):
             render("{% load flatpages %}{% get_flatpages %}")
-        with self.assertRaises(TemplateSyntaxError):
+        with self.assertRaisesMessage(TemplateSyntaxError, msg):
             render("{% load flatpages %}{% get_flatpages as %}")
-        with self.assertRaises(TemplateSyntaxError):
+        with self.assertRaisesMessage(TemplateSyntaxError, msg):
             render("{% load flatpages %}{% get_flatpages cheesecake flatpages %}")
-        with self.assertRaises(TemplateSyntaxError):
+        with self.assertRaisesMessage(TemplateSyntaxError, msg):
             render("{% load flatpages %}{% get_flatpages as flatpages asdf %}")
-        with self.assertRaises(TemplateSyntaxError):
+        with self.assertRaisesMessage(TemplateSyntaxError, msg):
             render("{% load flatpages %}{% get_flatpages cheesecake user as flatpages %}")
-        with self.assertRaises(TemplateSyntaxError):
+        with self.assertRaisesMessage(TemplateSyntaxError, msg):
             render("{% load flatpages %}{% get_flatpages for user as flatpages asdf %}")
-        with self.assertRaises(TemplateSyntaxError):
+        with self.assertRaisesMessage(TemplateSyntaxError, msg):
             render("{% load flatpages %}{% get_flatpages prefix for user as flatpages asdf %}")

tests/foreign_object/tests.py

@@ -369,7 +369,12 @@ def test_foreign_key_related_query_name(self):
         ArticleTag.objects.create(article=a1, name="foo")
         self.assertEqual(Article.objects.filter(tag__name="foo").count(), 1)
         self.assertEqual(Article.objects.filter(tag__name="bar").count(), 0)
-        with self.assertRaises(FieldError):
+        msg = (
+            "Cannot resolve keyword 'tags' into field. Choices are: "
+            "active_translation, active_translation_q, articletranslation, "
+            "id, idea_things, newsarticle, pub_date, tag"
+        )
+        with self.assertRaisesMessage(FieldError, msg):
             Article.objects.filter(tags__name="foo")
 
     def test_many_to_many_related_query_name(self):
@@ -378,7 +383,12 @@ def test_many_to_many_related_query_name(self):
         a1.ideas.add(i1)
         self.assertEqual(Article.objects.filter(idea_things__name="idea1").count(), 1)
         self.assertEqual(Article.objects.filter(idea_things__name="idea2").count(), 0)
-        with self.assertRaises(FieldError):
+        msg = (
+            "Cannot resolve keyword 'ideas' into field. Choices are: "
+            "active_translation, active_translation_q, articletranslation, "
+            "id, idea_things, newsarticle, pub_date, tag"
+        )
+        with self.assertRaisesMessage(FieldError, msg):
             Article.objects.filter(ideas__name="idea1")
 
     @translation.override('fi')

tests/forms_tests/field_tests/test_charfield.py

@@ -69,11 +69,12 @@ def test_charfield_length_not_int(self):
         Setting min_length or max_length to something that is not a number
         raises an exception.
         """
-        with self.assertRaises(ValueError):
+        msg = "invalid literal for int() with base 10: 'a'"
+        with self.assertRaisesMessage(ValueError, msg):
             CharField(min_length='a')
-        with self.assertRaises(ValueError):
+        with self.assertRaisesMessage(ValueError, msg):
             CharField(max_length='a')
-        with self.assertRaises(ValueError):
+        with self.assertRaisesMessage(ValueError, msg):
             CharField('a')
 
     def test_charfield_widget_attrs(self):

tests/forms_tests/field_tests/test_uuidfield.py

@@ -18,7 +18,8 @@ def test_uuidfield_2(self):
 
     def test_uuidfield_3(self):
         field = UUIDField()
-        with self.assertRaises(ValidationError) as cm:
+        msg = 'Enter a valid UUID.'
+        with self.assertRaisesMessage(ValidationError, msg) as cm:
             field.clean('550e8400')
         self.assertEqual(cm.exception.messages[0], 'Enter a valid UUID.')
 

tests/generic_relations/tests.py

@@ -347,7 +347,12 @@ def test_assign_with_queryset(self):
 
     def test_generic_relation_related_name_default(self):
         # GenericRelation isn't usable from the reverse side by default.
-        with self.assertRaises(FieldError):
+        msg = (
+            "Cannot resolve keyword 'vegetable' into field. Choices are: "
+            "animal, content_object, content_type, content_type_id, id, "
+            "manualpk, object_id, tag, valuabletaggeditem"
+        )
+        with self.assertRaisesMessage(FieldError, msg):
             TaggedItem.objects.filter(vegetable__isnull=True)
 
     def test_multiple_gfk(self):

tests/generic_views/test_edit.py

@@ -159,7 +159,8 @@ def test_create_with_special_properties(self):
         self.assertQuerysetEqual(Author.objects.all(), ['<Author: Randall Munroe>'])
 
     def test_create_without_redirect(self):
-        with self.assertRaises(ImproperlyConfigured):
+        msg = 'No URL to redirect to.  Either provide a url or define a get_absolute_url method on the Model.'
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
             self.client.post('/edit/authors/create/naive/', {'name': 'Randall Munroe', 'slug': 'randall-munroe'})
 
     def test_create_restricted(self):

tests/get_earliest_or_latest/tests.py

@@ -118,7 +118,8 @@ def test_latest_manual(self):
         # "get_latest_by" set -- just pass in the field name manually.
         Person.objects.create(name="Ralph", birthday=datetime(1950, 1, 1))
         p2 = Person.objects.create(name="Stephanie", birthday=datetime(1960, 2, 3))
-        with self.assertRaises(AssertionError):
+        msg = "earliest() and latest() require either a field_name parameter or 'get_latest_by' in the model"
+        with self.assertRaisesMessage(AssertionError, msg):
             Person.objects.latest()
         self.assertEqual(Person.objects.latest("birthday"), p2)
 

tests/lookup/tests.py

@@ -265,7 +265,11 @@ def test_values(self):
         # However, an exception FieldDoesNotExist will be thrown if you specify
         # a nonexistent field name in values() (a field that is neither in the
         # model nor in extra(select)).
-        with self.assertRaises(FieldError):
+        msg = (
+            "Cannot resolve keyword 'id_plus_two' into field. Choices are: "
+            "author, author_id, headline, id, id_plus_one, pub_date, tag"
+        )
+        with self.assertRaisesMessage(FieldError, msg):
             Article.objects.extra(select={'id_plus_one': 'id + 1'}).values('id', 'id_plus_two')
         # If you don't specify field names to values(), all are returned.
         self.assertSequenceEqual(
@@ -682,11 +686,16 @@ def test_nonfield_lookups(self):
         """
         A lookup query containing non-fields raises the proper exception.
         """
-        with self.assertRaises(FieldError):
+        msg = "Unsupported lookup 'blahblah' for CharField or join on the field not permitted."
+        with self.assertRaisesMessage(FieldError, msg):
             Article.objects.filter(headline__blahblah=99)
-        with self.assertRaises(FieldError):
+        with self.assertRaisesMessage(FieldError, msg):
             Article.objects.filter(headline__blahblah__exact=99)
-        with self.assertRaises(FieldError):
+        msg = (
+            "Cannot resolve keyword 'blahblah' into field. Choices are: "
+            "author, author_id, headline, id, pub_date, tag"
+        )
+        with self.assertRaisesMessage(FieldError, msg):
             Article.objects.filter(blahblah=99)
 
     def test_lookup_collision(self):

tests/m2m_regress/tests.py

@@ -102,7 +102,7 @@ def test_assigning_invalid_data_to_m2m_doesnt_clear_existing_relations(self):
         c1 = TagCollection.objects.create(name='c1')
         c1.tags.set([t1, t2])
 
-        with self.assertRaises(TypeError):
+        with self.assertRaisesMessage(TypeError, "'int' object is not iterable"):
             c1.tags.set(7)
 
         c1.refresh_from_db()

tests/model_fields/test_decimalfield.py

@@ -14,7 +14,8 @@ def test_to_python(self):
         f = models.DecimalField(max_digits=4, decimal_places=2)
         self.assertEqual(f.to_python(3), Decimal('3'))
         self.assertEqual(f.to_python('3.14'), Decimal('3.14'))
-        with self.assertRaises(ValidationError):
+        msg = "'abc' value must be a decimal number."
+        with self.assertRaisesMessage(ValidationError, msg):
             f.to_python('abc')
 
     def test_default(self):