Fixed #5416 -- Added TestCase.assertNumQueries, which tests that a given function executes the correct number of queries.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14183 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/__init__.py

@@ -21,6 +21,7 @@ class BaseDatabaseWrapper(local):
         self.settings_dict = settings_dict
         self.alias = alias
         self.vendor = 'unknown'
+        self.use_debug_cursor = None
 
     def __eq__(self, other):
         return self.settings_dict == other.settings_dict
@@ -74,7 +75,8 @@ class BaseDatabaseWrapper(local):
     def cursor(self):
         from django.conf import settings
         cursor = self._cursor()
-        if settings.DEBUG:
+        if (self.use_debug_cursor or
+            (self.use_debug_cursor is None and settings.DEBUG)):
             return self.make_debug_cursor(cursor)
         return cursor
 

django/test/testcases.py

@@ -1,4 +1,5 @@
 import re
+import sys
 from urlparse import urlsplit, urlunsplit
 from xml.dom.minidom import parseString, Node
 
@@ -205,6 +206,33 @@ class DocTestRunner(doctest.DocTestRunner):
         for conn in connections:
             transaction.rollback_unless_managed(using=conn)
 
+class _AssertNumQueriesContext(object):
+    def __init__(self, test_case, num, connection):
+        self.test_case = test_case
+        self.num = num
+        self.connection = connection
+
+    def __enter__(self):
+        self.old_debug_cursor = self.connection.use_debug_cursor
+        self.connection.use_debug_cursor = True
+        self.starting_queries = len(self.connection.queries)
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        if exc_type is not None:
+            return
+
+        self.connection.use_debug_cursor = self.old_debug_cursor
+        final_queries = len(self.connection.queries)
+        executed = final_queries - self.starting_queries
+
+        self.test_case.assertEqual(
+            executed, self.num, "%d queries executed, %d expected" % (
+                executed, self.num
+            )
+        )
+
+
 class TransactionTestCase(unittest.TestCase):
     # The class we'll use for the test client self.client.
     # Can be overridden in derived classes.
@@ -469,6 +497,22 @@ class TransactionTestCase(unittest.TestCase):
     def assertQuerysetEqual(self, qs, values, transform=repr):
         return self.assertEqual(map(transform, qs), values)
 
+    def assertNumQueries(self, num, func=None, *args, **kwargs):
+        using = kwargs.pop("using", DEFAULT_DB_ALIAS)
+        connection = connections[using]
+
+        context = _AssertNumQueriesContext(self, num, connection)
+        if func is None:
+            return context
+
+        # Basically emulate the `with` statement here.
+
+        context.__enter__()
+        try:
+            func(*args, **kwargs)
+        finally:
+            context.__exit__(*sys.exc_info())
+
 def connections_support_transactions():
     """
     Returns True if all connections support transactions.  This is messy

docs/topics/testing.txt

@@ -1372,6 +1372,32 @@ cause of an failure in your test suite.
     implicit ordering, you will need to apply a ``order_by()`` clause to your
     queryset to ensure that the test will pass reliably.
 
+.. method:: TestCase.assertNumQueries(num, func, *args, **kwargs):
+
+    .. versionadded:: 1.3
+
+    Asserts that when ``func`` is called with ``*args`` and ``**kwargs`` that
+    ``num`` database queries are executed.
+
+    If a ``"using"`` key is present in ``kwargs`` it is used as the database
+    alias for which to check the number of queries.  If you wish to call a
+    function with a ``using`` parameter you can do it by wrapping the call with
+    a ``lambda`` to add an extra parameter::
+
+        self.assertNumQueries(7, lambda: my_function(using=7))
+
+    If you're using Python 2.5 or greater you can also use this as a context
+    manager::
+
+        # This is necessary in Python 2.5 to enable the with statement, in 2.6
+        # and up it is no longer necessary.
+        from __future__ import with_statement
+
+        with self.assertNumQueries(2):
+            Person.objects.create(name="Aaron")
+            Person.objects.create(name="Daniel")
+
+
 .. _topics-testing-email:
 
 E-mail services

tests/modeltests/select_related/tests.py

@@ -1,6 +1,4 @@
 from django.test import TestCase
-from django.conf import settings
-from django import db
 
 from models import Domain, Kingdom, Phylum, Klass, Order, Family, Genus, Species
 
@@ -36,73 +34,73 @@ class SelectRelatedTests(TestCase):
         # queries so we'll set it to True here and reset it at the end of the
         # test case.
         self.create_base_data()
-        settings.DEBUG = True
-        db.reset_queries()
-
-    def tearDown(self):
-        settings.DEBUG = False
 
     def test_access_fks_without_select_related(self):
         """
         Normally, accessing FKs doesn't fill in related objects
         """
-        fly = Species.objects.get(name="melanogaster")
-        domain = fly.genus.family.order.klass.phylum.kingdom.domain
-        self.assertEqual(domain.name, 'Eukaryota')
-        self.assertEqual(len(db.connection.queries), 8)
+        def test():
+            fly = Species.objects.get(name="melanogaster")
+            domain = fly.genus.family.order.klass.phylum.kingdom.domain
+            self.assertEqual(domain.name, 'Eukaryota')
+        self.assertNumQueries(8, test)
 
     def test_access_fks_with_select_related(self):
         """
         A select_related() call will fill in those related objects without any
         extra queries
         """
-        person = Species.objects.select_related(depth=10).get(name="sapiens")
-        domain = person.genus.family.order.klass.phylum.kingdom.domain
-        self.assertEqual(domain.name, 'Eukaryota')
-        self.assertEqual(len(db.connection.queries), 1)
+        def test():
+            person = Species.objects.select_related(depth=10).get(name="sapiens")
+            domain = person.genus.family.order.klass.phylum.kingdom.domain
+            self.assertEqual(domain.name, 'Eukaryota')
+        self.assertNumQueries(1, test)
 
     def test_list_without_select_related(self):
         """
         select_related() also of course applies to entire lists, not just
         items. This test verifies the expected behavior without select_related.
         """
-        world = Species.objects.all()
-        families = [o.genus.family.name for o in world]
-        self.assertEqual(families, [
-            'Drosophilidae',
-            'Hominidae',
-            'Fabaceae',
-            'Amanitacae',
-        ])
-        self.assertEqual(len(db.connection.queries), 9)
+        def test():
+            world = Species.objects.all()
+            families = [o.genus.family.name for o in world]
+            self.assertEqual(families, [
+                'Drosophilidae',
+                'Hominidae',
+                'Fabaceae',
+                'Amanitacae',
+            ])
+        self.assertNumQueries(9, test)
 
     def test_list_with_select_related(self):
         """
         select_related() also of course applies to entire lists, not just
         items. This test verifies the expected behavior with select_related.
         """
-        world = Species.objects.all().select_related()
-        families = [o.genus.family.name for o in world]
-        self.assertEqual(families, [
-            'Drosophilidae',
-            'Hominidae',
-            'Fabaceae',
-            'Amanitacae',
-        ])
-        self.assertEqual(len(db.connection.queries), 1)
+        def test():
+            world = Species.objects.all().select_related()
+            families = [o.genus.family.name for o in world]
+            self.assertEqual(families, [
+                'Drosophilidae',
+                'Hominidae',
+                'Fabaceae',
+                'Amanitacae',
+            ])
+        self.assertNumQueries(1, test)
 
     def test_depth(self, depth=1, expected=7):
         """
         The "depth" argument to select_related() will stop the descent at a
         particular level.
         """
-        pea = Species.objects.select_related(depth=depth).get(name="sativum")
-        self.assertEqual(
-            pea.genus.family.order.klass.phylum.kingdom.domain.name,
-            'Eukaryota'
-        )
+        def test():
+            pea = Species.objects.select_related(depth=depth).get(name="sativum")
+            self.assertEqual(
+                pea.genus.family.order.klass.phylum.kingdom.domain.name,
+                'Eukaryota'
+            )
         # Notice: one fewer queries than above because of depth=1
-        self.assertEqual(len(db.connection.queries), expected)
+        self.assertNumQueries(expected, test)
 
     def test_larger_depth(self):
         """
@@ -116,11 +114,12 @@ class SelectRelatedTests(TestCase):
         The "depth" argument to select_related() will stop the descent at a
         particular level. This can be used on lists as well.
         """
-        world = Species.objects.all().select_related(depth=2)
-        orders = [o.genus.family.order.name for o in world]
-        self.assertEqual(orders,
-            ['Diptera', 'Primates', 'Fabales', 'Agaricales'])
-        self.assertEqual(len(db.connection.queries), 5)
+        def test():
+            world = Species.objects.all().select_related(depth=2)
+            orders = [o.genus.family.order.name for o in world]
+            self.assertEqual(orders,
+                ['Diptera', 'Primates', 'Fabales', 'Agaricales'])
+        self.assertNumQueries(5, test)
 
     def test_select_related_with_extra(self):
         s = Species.objects.all().select_related(depth=1)\
@@ -136,28 +135,31 @@ class SelectRelatedTests(TestCase):
         In this case, we explicitly say to select the 'genus' and
         'genus.family' models, leading to the same number of queries as before.
         """
-        world = Species.objects.select_related('genus__family')
-        families = [o.genus.family.name for o in world]
-        self.assertEqual(families,
-            ['Drosophilidae', 'Hominidae', 'Fabaceae', 'Amanitacae'])
-        self.assertEqual(len(db.connection.queries), 1)
+        def test():
+            world = Species.objects.select_related('genus__family')
+            families = [o.genus.family.name for o in world]
+            self.assertEqual(families,
+                ['Drosophilidae', 'Hominidae', 'Fabaceae', 'Amanitacae'])
+        self.assertNumQueries(1, test)
 
     def test_more_certain_fields(self):
         """
         In this case, we explicitly say to select the 'genus' and
         'genus.family' models, leading to the same number of queries as before.
         """
-        world = Species.objects.filter(genus__name='Amanita')\
-            .select_related('genus__family')
-        orders = [o.genus.family.order.name for o in world]
-        self.assertEqual(orders, [u'Agaricales'])
-        self.assertEqual(len(db.connection.queries), 2)
+        def test():
+            world = Species.objects.filter(genus__name='Amanita')\
+                .select_related('genus__family')
+            orders = [o.genus.family.order.name for o in world]
+            self.assertEqual(orders, [u'Agaricales'])
+        self.assertNumQueries(2, test)
 
     def test_field_traversal(self):
-        s = Species.objects.all().select_related('genus__family__order'
-            ).order_by('id')[0:1].get().genus.family.order.name
-        self.assertEqual(s, u'Diptera')
-        self.assertEqual(len(db.connection.queries), 1)
+        def test():
+            s = Species.objects.all().select_related('genus__family__order'
+                ).order_by('id')[0:1].get().genus.family.order.name
+            self.assertEqual(s, u'Diptera')
+        self.assertNumQueries(1, test)
 
     def test_depth_fields_fails(self):
         self.assertRaises(TypeError,

tests/modeltests/validation/test_unique.py

@@ -2,9 +2,11 @@ import datetime
 
 from django.conf import settings
 from django.db import connection
+from django.test import TestCase
 from django.utils import unittest
 
-from models import CustomPKModel, UniqueTogetherModel, UniqueFieldsModel, UniqueForDateModel, ModelToValidate
+from models import (CustomPKModel, UniqueTogetherModel, UniqueFieldsModel,
+    UniqueForDateModel, ModelToValidate)
 
 
 class GetUniqueCheckTests(unittest.TestCase):
@@ -51,37 +53,26 @@ class GetUniqueCheckTests(unittest.TestCase):
             ), m._get_unique_checks(exclude='start_date')
         )
 
-class PerformUniqueChecksTest(unittest.TestCase):
-    def setUp(self):
-        # Set debug to True to gain access to connection.queries.
-        self._old_debug, settings.DEBUG = settings.DEBUG, True
-        super(PerformUniqueChecksTest, self).setUp()
-
-    def tearDown(self):
-        # Restore old debug value.
-        settings.DEBUG = self._old_debug
-        super(PerformUniqueChecksTest, self).tearDown()
-
+class PerformUniqueChecksTest(TestCase):
     def test_primary_key_unique_check_not_performed_when_adding_and_pk_not_specified(self):
         # Regression test for #12560
-        query_count = len(connection.queries)
-        mtv = ModelToValidate(number=10, name='Some Name')
-        setattr(mtv, '_adding', True)
-        mtv.full_clean()
-        self.assertEqual(query_count, len(connection.queries))
+        def test():
+            mtv = ModelToValidate(number=10, name='Some Name')
+            setattr(mtv, '_adding', True)
+            mtv.full_clean()
+        self.assertNumQueries(0, test)
 
     def test_primary_key_unique_check_performed_when_adding_and_pk_specified(self):
         # Regression test for #12560
-        query_count = len(connection.queries)
-        mtv = ModelToValidate(number=10, name='Some Name', id=123)
-        setattr(mtv, '_adding', True)
-        mtv.full_clean()
-        self.assertEqual(query_count + 1, len(connection.queries))
+        def test():
+            mtv = ModelToValidate(number=10, name='Some Name', id=123)
+            setattr(mtv, '_adding', True)
+            mtv.full_clean()
+        self.assertNumQueries(1, test)
 
     def test_primary_key_unique_check_not_performed_when_not_adding(self):
         # Regression test for #12132
-        query_count= len(connection.queries)
-        mtv = ModelToValidate(number=10, name='Some Name')
-        mtv.full_clean()
-        self.assertEqual(query_count, len(connection.queries))
-
+        def test():
+            mtv = ModelToValidate(number=10, name='Some Name')
+            mtv.full_clean()
+        self.assertNumQueries(0, test)

tests/modeltests/validation/tests.py

@@ -6,7 +6,8 @@ from modeltests.validation.models import Author, Article, ModelToValidate
 
 # Import other tests for this package.
 from modeltests.validation.validators import TestModelsWithValidators
-from modeltests.validation.test_unique import GetUniqueCheckTests, PerformUniqueChecksTest
+from modeltests.validation.test_unique import (GetUniqueCheckTests,
+    PerformUniqueChecksTest)
 from modeltests.validation.test_custom_messages import CustomMessagesTest
 
 
@@ -111,4 +112,3 @@ class ModelFormsTests(TestCase):
         article = Article(author_id=self.author.id)
         form = ArticleForm(data, instance=article)
         self.assertEqual(form.errors.keys(), ['pub_date'])
-

tests/regressiontests/defer_regress/tests.py

@@ -11,17 +11,6 @@ from models import ResolveThis, Item, RelatedItem, Child, Leaf
 
 
 class DeferRegressionTest(TestCase):
-    def assert_num_queries(self, n, func, *args, **kwargs):
-        old_DEBUG = settings.DEBUG
-        settings.DEBUG = True
-        starting_queries = len(connection.queries)
-        try:
-            func(*args, **kwargs)
-        finally:
-            settings.DEBUG = old_DEBUG
-        self.assertEqual(starting_queries + n, len(connection.queries))
-
-
     def test_basic(self):
         # Deferred fields should really be deferred and not accidentally use
         # the field's default value just because they aren't passed to __init__
@@ -33,19 +22,19 @@ class DeferRegressionTest(TestCase):
         def test():
             self.assertEqual(obj.name, "first")
             self.assertEqual(obj.other_value, 0)
-        self.assert_num_queries(0, test)
+        self.assertNumQueries(0, test)
 
         def test():
             self.assertEqual(obj.value, 42)
-        self.assert_num_queries(1, test)
+        self.assertNumQueries(1, test)
 
         def test():
             self.assertEqual(obj.text, "xyzzy")
-        self.assert_num_queries(1, test)
+        self.assertNumQueries(1, test)
 
         def test():
             self.assertEqual(obj.text, "xyzzy")
-        self.assert_num_queries(0, test)
+        self.assertNumQueries(0, test)
 
         # Regression test for #10695. Make sure different instances don't
         # inadvertently share data in the deferred descriptor objects.

tests/regressiontests/forms/models.py

@@ -1,10 +1,9 @@
 # -*- coding: utf-8 -*-
 import datetime
-import tempfile
 import shutil
+import tempfile
 
-from django.db import models, connection
-from django.conf import settings
+from django.db import models
 # Can't import as "forms" due to implementation details in the test suite (the
 # current file is called "forms" and is already imported).
 from django import forms as django_forms
@@ -77,19 +76,13 @@ class TestTicket12510(TestCase):
     ''' It is not necessary to generate choices for ModelChoiceField (regression test for #12510). '''
     def setUp(self):
         self.groups = [Group.objects.create(name=name) for name in 'abc']
-        self.old_debug = settings.DEBUG
-        # turn debug on to get access to connection.queries
-        settings.DEBUG = True
-
-    def tearDown(self):
-        settings.DEBUG = self.old_debug
 
     def test_choices_not_fetched_when_not_rendering(self):
-        initial_queries = len(connection.queries)
-        field = django_forms.ModelChoiceField(Group.objects.order_by('-name'))
-        self.assertEqual('a', field.clean(self.groups[0].pk).name)
+        def test():
+            field = django_forms.ModelChoiceField(Group.objects.order_by('-name'))
+            self.assertEqual('a', field.clean(self.groups[0].pk).name)
         # only one query is required to pull the model from DB
-        self.assertEqual(initial_queries+1, len(connection.queries))
+        self.assertNumQueries(1, test)
 
 class ModelFormCallableModelDefault(TestCase):
     def test_no_empty_option(self):

tests/regressiontests/model_forms_regress/tests.py

@@ -1,10 +1,8 @@
 import unittest
 from datetime import date
 
-from django import db
 from django import forms
 from django.forms.models import modelform_factory, ModelChoiceField
-from django.conf import settings
 from django.test import TestCase
 from django.core.exceptions import FieldError, ValidationError
 from django.core.files.uploadedfile import SimpleUploadedFile
@@ -14,14 +12,6 @@ from models import Person, RealPerson, Triple, FilePathModel, Article, \
 
 
 class ModelMultipleChoiceFieldTests(TestCase):
-
-    def setUp(self):
-        self.old_debug = settings.DEBUG
-        settings.DEBUG = True
-
-    def tearDown(self):
-        settings.DEBUG = self.old_debug
-
     def test_model_multiple_choice_number_of_queries(self):
         """
         Test that ModelMultipleChoiceField does O(1) queries instead of
@@ -30,10 +20,8 @@ class ModelMultipleChoiceFieldTests(TestCase):
         for i in range(30):
             Person.objects.create(name="Person %s" % i)
 
-        db.reset_queries()
         f = forms.ModelMultipleChoiceField(queryset=Person.objects.all())
-        selected = f.clean([1, 3, 5, 7, 9])
-        self.assertEquals(len(db.connection.queries), 1)
+        self.assertNumQueries(1, f.clean, [1, 3, 5, 7, 9])
 
 class TripleForm(forms.ModelForm):
     class Meta:

tests/regressiontests/select_related_onetoone/tests.py

@@ -7,11 +7,6 @@ from models import (User, UserProfile, UserStat, UserStatResult, StatDetails,
 
 class ReverseSelectRelatedTestCase(TestCase):
     def setUp(self):
-        # Explicitly enable debug for these tests - we need to count
-        # the queries that have been issued.
-        self.old_debug = settings.DEBUG
-        settings.DEBUG = True
-
         user = User.objects.create(username="test")
         userprofile = UserProfile.objects.create(user=user, state="KS",
                                                  city="Lawrence")
@@ -26,65 +21,66 @@ class ReverseSelectRelatedTestCase(TestCase):
                                                   results=results2)
         StatDetails.objects.create(base_stats=advstat, comments=250)
 
-        db.reset_queries()
-
-    def assertQueries(self, queries):
-        self.assertEqual(len(db.connection.queries), queries)
-
-    def tearDown(self):
-        settings.DEBUG = self.old_debug
-
     def test_basic(self):
-        u = User.objects.select_related("userprofile").get(username="test")
-        self.assertEqual(u.userprofile.state, "KS")
-        self.assertQueries(1)
+        def test():
+            u = User.objects.select_related("userprofile").get(username="test")
+            self.assertEqual(u.userprofile.state, "KS")
+        self.assertNumQueries(1, test)
 
     def test_follow_next_level(self):
-        u = User.objects.select_related("userstat__results").get(username="test")
-        self.assertEqual(u.userstat.posts, 150)
-        self.assertEqual(u.userstat.results.results, 'first results')
-        self.assertQueries(1)
+        def test():
+            u = User.objects.select_related("userstat__results").get(username="test")
+            self.assertEqual(u.userstat.posts, 150)
+            self.assertEqual(u.userstat.results.results, 'first results')
+        self.assertNumQueries(1, test)
 
     def test_follow_two(self):
-        u = User.objects.select_related("userprofile", "userstat").get(username="test")
-        self.assertEqual(u.userprofile.state, "KS")
-        self.assertEqual(u.userstat.posts, 150)
-        self.assertQueries(1)
+        def test():
+            u = User.objects.select_related("userprofile", "userstat").get(username="test")
+            self.assertEqual(u.userprofile.state, "KS")
+            self.assertEqual(u.userstat.posts, 150)
+        self.assertNumQueries(1, test)
 
     def test_follow_two_next_level(self):
-        u = User.objects.select_related("userstat__results", "userstat__statdetails").get(username="test")
-        self.assertEqual(u.userstat.results.results, 'first results')
-        self.assertEqual(u.userstat.statdetails.comments, 259)
-        self.assertQueries(1)
+        def test():
+            u = User.objects.select_related("userstat__results", "userstat__statdetails").get(username="test")
+            self.assertEqual(u.userstat.results.results, 'first results')
+            self.assertEqual(u.userstat.statdetails.comments, 259)
+        self.assertNumQueries(1, test)
 
     def test_forward_and_back(self):
-        stat = UserStat.objects.select_related("user__userprofile").get(user__username="test")
-        self.assertEqual(stat.user.userprofile.state, 'KS')
-        self.assertEqual(stat.user.userstat.posts, 150)
-        self.assertQueries(1)
+        def test():
+            stat = UserStat.objects.select_related("user__userprofile").get(user__username="test")
+            self.assertEqual(stat.user.userprofile.state, 'KS')
+            self.assertEqual(stat.user.userstat.posts, 150)
+        self.assertNumQueries(1, test)
 
     def test_back_and_forward(self):
-        u = User.objects.select_related("userstat").get(username="test")
-        self.assertEqual(u.userstat.user.username, 'test')
-        self.assertQueries(1)
+        def test():
+            u = User.objects.select_related("userstat").get(username="test")
+            self.assertEqual(u.userstat.user.username, 'test')
+        self.assertNumQueries(1, test)
 
     def test_not_followed_by_default(self):
-        u = User.objects.select_related().get(username="test")
-        self.assertEqual(u.userstat.posts, 150)
-        self.assertQueries(2)
+        def test():
+            u = User.objects.select_related().get(username="test")
+            self.assertEqual(u.userstat.posts, 150)
+        self.assertNumQueries(2, test)
 
     def test_follow_from_child_class(self):
-        stat = AdvancedUserStat.objects.select_related('user', 'statdetails').get(posts=200)
-        self.assertEqual(stat.statdetails.comments, 250)
-        self.assertEqual(stat.user.username, 'bob')
-        self.assertQueries(1)
+        def test():
+            stat = AdvancedUserStat.objects.select_related('user', 'statdetails').get(posts=200)
+            self.assertEqual(stat.statdetails.comments, 250)
+            self.assertEqual(stat.user.username, 'bob')
+        self.assertNumQueries(1, test)
 
     def test_follow_inheritance(self):
-        stat = UserStat.objects.select_related('user', 'advanceduserstat').get(posts=200)
-        self.assertEqual(stat.advanceduserstat.posts, 200)
-        self.assertEqual(stat.user.username, 'bob')
-        self.assertEqual(stat.advanceduserstat.user.username, 'bob')
-        self.assertQueries(1)
+        def test():
+            stat = UserStat.objects.select_related('user', 'advanceduserstat').get(posts=200)
+            self.assertEqual(stat.advanceduserstat.posts, 200)
+            self.assertEqual(stat.user.username, 'bob')
+            self.assertEqual(stat.advanceduserstat.user.username, 'bob')
+        self.assertNumQueries(1, test)
 
     def test_nullable_relation(self):
         im = Image.objects.create(name="imag1")

tests/regressiontests/test_utils/models.py

@@ -0,0 +1,5 @@
+from django.db import models
+
+
+class Person(models.Model):
+    name = models.CharField(max_length=100)

tests/regressiontests/test_utils/python_25.py

@@ -0,0 +1,30 @@
+from __future__ import with_statement
+
+from django.test import TestCase
+
+from models import Person
+
+
+class AssertNumQueriesTests(TestCase):
+    def test_simple(self):
+        with self.assertNumQueries(0):
+            pass
+
+        with self.assertNumQueries(1):
+            # Guy who wrote Linux
+            Person.objects.create(name="Linus Torvalds")
+
+        with self.assertNumQueries(2):
+            # Guy who owns the bagel place I like
+            Person.objects.create(name="Uncle Ricky")
+            self.assertEqual(Person.objects.count(), 2)
+
+    def test_failure(self):
+        with self.assertRaises(AssertionError) as exc_info:
+            with self.assertNumQueries(2):
+                Person.objects.count()
+        self.assertEqual(str(exc_info.exception), "1 != 2 : 1 queries executed, 2 expected")
+
+        with self.assertRaises(TypeError):
+            with self.assertNumQueries(4000):
+                raise TypeError

tests/regressiontests/test_utils/tests.py

@@ -1,4 +1,10 @@
-r"""
+import sys
+
+if sys.version_info >= (2, 5):
+    from python_25 import AssertNumQueriesTests
+
+
+__test__ = {"API_TEST": r"""
 # Some checks of the doctest output normalizer.
 # Standard doctests do fairly
 >>> from django.utils import simplejson
@@ -69,4 +75,4 @@ r"""
 >>> produce_xml_fragment()
 '<foo bbb="2.0" aaa="1.0">Hello</foo><bar ddd="4.0" ccc="3.0"></bar>'
 
-"""
+"""}