Refs #36064 -- Added test that falsey primary key default/db_default value skips an update query on save.

This adds test coverage for logic change in 9fa4d07ce0729850661a31a6b37c6b48f13d2266.

tests/basic/models.py

@@ -57,5 +57,13 @@ class PrimaryKeyWithDbDefault(models.Model):
     uuid = models.IntegerField(primary_key=True, db_default=1)
 
 
+class PrimaryKeyWithFalseyDefault(models.Model):
+    uuid = models.IntegerField(primary_key=True, default=0)
+
+
+class PrimaryKeyWithFalseyDbDefault(models.Model):
+    uuid = models.IntegerField(primary_key=True, db_default=0)
+
+
 class ChildPrimaryKeyWithDefault(PrimaryKeyWithDefault):
     pass

tests/basic/tests.py

@@ -32,6 +32,8 @@ from .models import (
     FeaturedArticle,
     PrimaryKeyWithDbDefault,
     PrimaryKeyWithDefault,
+    PrimaryKeyWithFalseyDbDefault,
+    PrimaryKeyWithFalseyDefault,
     SelfRef,
 )
 
@@ -203,6 +205,14 @@ class ModelInstanceCreationTests(TestCase):
         with self.assertNumQueries(2):
             ChildPrimaryKeyWithDefault().save()
 
+    def test_save_primary_with_falsey_default(self):
+        with self.assertNumQueries(1):
+            PrimaryKeyWithFalseyDefault().save()
+
+    def test_save_primary_with_falsey_db_default(self):
+        with self.assertNumQueries(1):
+            PrimaryKeyWithFalseyDbDefault().save()
+
     def test_save_deprecation(self):
         a = Article(headline="original", pub_date=datetime(2014, 5, 16))
         msg = "Passing positional arguments to save() is deprecated"