Add unblock test case when both flags are set

Author: Lode Rosseel

tests/test_fixtures.py

@@ -750,6 +750,11 @@ def test_unblock_with_block(self, django_db_blocker: DjangoDbBlocker) -> None:
         with django_db_blocker.unblock():
             Item.objects.exists()
 
+    def test_unblock_with_both_flags_raises_valueerror(self, django_db_blocker: DjangoDbBlocker) -> None:
+        # When both sync_only and async_only are True, unblock should reject with ValueError
+        with pytest.raises(ValueError, match="Cannot use both sync_only and async_only"):
+            django_db_blocker.unblock(sync_only=True, async_only=True)
+
 
 def test_mail(mailoutbox) -> None:
     assert mailoutbox is mail.outbox  # check that mail.outbox and fixture value is same object