Fixed #28203 -- Ignored connection configuration queries in assertNumQueries().

django/test/utils.py

@@ -601,6 +601,9 @@ class CaptureQueriesContext:
     def __enter__(self):
         self.force_debug_cursor = self.connection.force_debug_cursor
         self.connection.force_debug_cursor = True
+        # Run any initialization queries if needed so that they won't be
+        # included as part of the count.
+        self.connection.ensure_connection()
         self.initial_queries = len(self.connection.queries_log)
         self.final_queries = None
         request_started.disconnect(reset_queries)

docs/releases/2.0.txt

@@ -334,6 +334,11 @@ Miscellaneous
 * The ``FIRST_DAY_OF_WEEK`` and ``NUMBER_GROUPING`` format settings are now
   kept as integers in JavaScript and JSON i18n view outputs.
 
+* :meth:`~django.test.TransactionTestCase.assertNumQueries` now ignores
+  connection configuration queries. Previously, if a test opened a new database
+  connection, those queries could be included as part of the
+  ``assertNumQueries()`` count.
+
 .. _deprecated-features-2.0:
 
 Features deprecated in 2.0

tests/test_utils/tests.py

@@ -14,7 +14,8 @@ from django.forms import EmailField, IntegerField
 from django.http import HttpResponse
 from django.template.loader import render_to_string
 from django.test import (
-    SimpleTestCase, TestCase, skipIfDBFeature, skipUnlessDBFeature,
+    SimpleTestCase, TestCase, TransactionTestCase, skipIfDBFeature,
+    skipUnlessDBFeature,
 )
 from django.test.html import HTMLParseError, parse_html
 from django.test.utils import (
@@ -157,6 +158,32 @@ class AssertNumQueriesTests(TestCase):
         self.assertNumQueries(2, test_func)
 
 
+@unittest.skipUnless(
+    connection.vendor != 'sqlite' or not connection.is_in_memory_db(),
+    'For SQLite in-memory tests, closing the connection destroys the database.'
+)
+class AssertNumQueriesUponConnectionTests(TransactionTestCase):
+    available_apps = []
+
+    def test_ignores_connection_configuration_queries(self):
+        real_ensure_connection = connection.ensure_connection
+        connection.close()
+
+        def make_configuration_query():
+            is_opening_connection = connection.connection is None
+            real_ensure_connection()
+
+            if is_opening_connection:
+                # Avoid infinite recursion. Creating a cursor calls
+                # ensure_connection() which is currently mocked by this method.
+                connection.cursor().execute('SELECT 1' + connection.features.bare_select_suffix)
+
+        ensure_connection = 'django.db.backends.base.base.BaseDatabaseWrapper.ensure_connection'
+        with mock.patch(ensure_connection, side_effect=make_configuration_query):
+            with self.assertNumQueries(1):
+                list(Car.objects.all())
+
+
 class AssertQuerysetEqualTests(TestCase):
     def setUp(self):
         self.p1 = Person.objects.create(name='p1')