Fixed #17653 -- Allowed using zero as AutoFields value on MySQL if NO_AUTO_VALUE_ON_ZERO SQL mode is enabled.

4 files changed, 12 insertions, 4 deletions

diff --git a/tests/backends/mysql/test_features.py b/tests/backends/mysql/test_features.py
index 1385c9b88c..5d27890a5d 100644
--- a/tests/backends/mysql/test_features.py
+++ b/tests/backends/mysql/test_features.py
@@ -32,3 +32,9 @@ class TestFeatures(TestCase):
             database_features = DatabaseFeatures(_connection)
             self.assertFalse(database_features.has_select_for_update_skip_locked)
             self.assertFalse(database_features.has_select_for_update_nowait)
+
+    def test_allows_auto_pk_0(self):
+        with mock.MagicMock() as _connection:
+            _connection.sql_mode = {'NO_AUTO_VALUE_ON_ZERO'}
+            database_features = DatabaseFeatures(_connection)
+            self.assertIs(database_features.allows_auto_pk_0, True)
diff --git a/tests/backends/tests.py b/tests/backends/tests.py
index 08bdac3437..cf6bdbf25d 100644
--- a/tests/backends/tests.py
+++ b/tests/backends/tests.py
@@ -806,7 +806,8 @@ class ThreadTests(TransactionTestCase):
 class MySQLPKZeroTests(TestCase):
     """
     Zero as id for AutoField should raise exception in MySQL, because MySQL
-    does not allow zero for autoincrement primary key.
+    does not allow zero for autoincrement primary key if the
+    NO_AUTO_VALUE_ON_ZERO SQL mode is not enabled.
     """
     @skipIfDBFeature('allows_auto_pk_0')
     def test_zero_as_autoval(self):
diff --git a/tests/bulk_create/tests.py b/tests/bulk_create/tests.py
index ff89bcb1dd..2b1d901e31 100644
--- a/tests/bulk_create/tests.py
+++ b/tests/bulk_create/tests.py
@@ -115,7 +115,8 @@ class BulkCreateTests(TestCase):
     def test_zero_as_autoval(self):
         """
         Zero as id for AutoField should raise exception in MySQL, because MySQL
-        does not allow zero for automatic primary key.
+        does not allow zero for automatic primary key if the
+        NO_AUTO_VALUE_ON_ZERO SQL mode is not enabled.
         """
         valid_country = Country(name='Germany', iso_two_letter='DE')
         invalid_country = Country(id=0, name='Poland', iso_two_letter='PL')
diff --git a/tests/serializers/test_data.py b/tests/serializers/test_data.py
index 1ddba02565..323cb13e82 100644
--- a/tests/serializers/test_data.py
+++ b/tests/serializers/test_data.py
@@ -379,8 +379,8 @@ if connection.features.interprets_empty_strings_as_nulls:
                          data[3] is None)]
 
 # Regression test for #8651 -- a FK to an object with PK of 0
-# This won't work on MySQL since it won't let you create an object
-# with an autoincrement primary key of 0,
+# This won't work on MySQL without the NO_AUTO_VALUE_ON_ZERO SQL mode since it
+# won't let you create an object with an autoincrement primary key of 0.
 if connection.features.allows_auto_pk_0:
     test_data.extend([
         (data_obj, 0, Anchor, "Anchor 0"),