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

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