[tests] Add regression test for manage_devices_group_templates

Ensures the loop does not terminate early when a device in the batch
has no config. The second device must still receive group templates
even if the first device is skipped.

Author: mn-ram

openwisp_controller/config/tests/test_device_group.py

@@ -9,12 +9,16 @@
 
 from .. import settings as app_settings
 from ..signals import group_templates_changed
-from .utils import CreateDeviceGroupMixin, CreateTemplateMixin
+from .utils import CreateDeviceGroupMixin, CreateDeviceMixin, CreateTemplateMixin
 
+Device = load_model("config", "Device")
 DeviceGroup = load_model("config", "DeviceGroup")
+Template = load_model("config", "Template")
 
 
-class TestDeviceGroup(CreateDeviceGroupMixin, CreateTemplateMixin, TestCase):
+class TestDeviceGroup(
+    CreateDeviceMixin, CreateDeviceGroupMixin, CreateTemplateMixin, TestCase
+):
     def test_device_group(self):
         self._create_device_group(
             meta_data={"captive_portal_url": "https//example.com"}
@@ -61,3 +65,53 @@ def test_device_group_signals(self):
                 raw=False,
                 using="default",
             )
+
+    def test_manage_devices_group_templates_no_early_termination(self):
+        """
+        Regression test: when the first device in the batch has no config
+        (because its group has no templates), the loop must continue and
+        still apply group templates to the second device.
+        """
+        org = self._get_org()
+        t1 = self._create_template(name="t1")
+        # group_with_templates has a template; group_without does not
+        group_with_templates = self._create_device_group(
+            name="group-with-tpl", organization=org
+        )
+        group_with_templates.templates.add(t1)
+        group_without_templates = self._create_device_group(
+            name="group-without-tpl", organization=org
+        )
+        # device1: belongs to a group without templates → no config created
+        device1 = self._create_device(
+            name="device-no-config",
+            organization=org,
+            group=group_without_templates,
+            mac_address="00:00:00:00:00:01",
+        )
+        self.assertFalse(hasattr(device1, "config"))
+        # device2: has a config object
+        device2 = self._create_device(
+            name="device-with-config",
+            organization=org,
+            mac_address="00:00:00:00:00:02",
+        )
+        from openwisp_controller.config.tests.utils import Config
+
+        Config.objects.create(
+            device=device2,
+            backend="netjsonconfig.OpenWrt",
+        )
+        device2.refresh_from_db()
+        self.assertTrue(hasattr(device2, "config"))
+        self.assertEqual(device2.config.templates.count(), 0)
+        # Call manage_devices_group_templates with device1 (no config) first,
+        # then device2 (has config). device1 should be skipped, device2 must
+        # still get group_with_templates's template applied.
+        Device.manage_devices_group_templates(
+            device_ids=[device1.pk, device2.pk],
+            old_group_ids=[None, None],
+            group_id=group_with_templates.pk,
+        )
+        device2.refresh_from_db()
+        self.assertIn(t1, device2.config.templates.all())