Fixed #21462 -- Made `assertNumQueries` print executed queries on failure.

django/test/testcases.py

@@ -103,8 +103,12 @@ class _AssertNumQueriesContext(CaptureQueriesContext):
             return
         executed = len(self)
         self.test_case.assertEqual(
-            executed, self.num, "%d queries executed, %d expected" % (
+            executed, self.num,
-                executed, self.num
+            "%d queries executed, %d expected\nCaptured queries were:\n%s" % (
+                executed, self.num,
+                '\n'.join(
+                    query['sql'] for query in self.captured_queries
+                )
             )
         )
 

docs/releases/1.7.txt

@@ -713,6 +713,9 @@ Miscellaneous
   ``select_related('foo').select_related('bar')``. Previously the latter would
   have been equivalent to ``select_related('bar')``.
 
+* :meth:`~django.test.TransactionTestCase.assertNumQueries` now prints
+  out the list of executed queries if the assertion fails.
+
 Features deprecated in 1.7
 ==========================
 

tests/test_utils/tests.py

@@ -192,6 +192,7 @@ class AssertNumQueriesContextManagerTests(TestCase):
             with self.assertNumQueries(2):
                 Person.objects.count()
         self.assertIn("1 queries executed, 2 expected", str(exc_info.exception))
+        self.assertIn("Captured queries were", str(exc_info.exception))
 
         with self.assertRaises(TypeError):
             with self.assertNumQueries(4000):