test(api): cover scan-perform no-op when provider is deleted

Adds unit tests asserting perform_scan_task and
perform_scheduled_scan_task return None without raising or calling
perform_prowler_scan when the target provider does not exist. Also
records the fix in api/CHANGELOG.md under 1.28.0.

Author: AdriiiPRodri

api/CHANGELOG.md

@@ -13,6 +13,10 @@ All notable changes to the **Prowler API** are documented in this file.
 - Replace `poetry` with `uv` (`0.11.14`) as the API package manager; migrate `pyproject.toml` to `[dependency-groups]` and regenerate as `uv.lock` [(#10775)](https://github.com/prowler-cloud/prowler/pull/10775)
 - Remove orphaned `gin_resources_search_idx` declaration from `Resource.Meta.indexes` (DB index dropped in `0072_drop_unused_indexes`) [(#11001)](https://github.com/prowler-cloud/prowler/pull/11001)
 
+### 🐞 Fixed
+
+- `perform_scan_task` and `perform_scheduled_scan_task` now short-circuit with a warning and `return None` when the target provider no longer exists, instead of letting `handle_provider_deletion` raise `ProviderDeletedException`. Prevents queued messages for deleted providers from being recorded as `FAILURE` and, in one-shot scan-worker deployments, from burning a fresh container per redelivery [(#11185)](https://github.com/prowler-cloud/prowler/pull/11185)
+
 ---
 
 ## [1.27.2] (Prowler UNRELEASED)

api/src/backend/tasks/tests/test_tasks.py

@@ -21,6 +21,7 @@
     check_lighthouse_provider_connection_task,
     generate_outputs_task,
     perform_attack_paths_scan_task,
+    perform_scan_task,
     perform_scheduled_scan_task,
     reaggregate_all_finding_group_summaries_task,
     refresh_lighthouse_provider_models_task,
@@ -1433,9 +1434,9 @@ def factory(*args, **kwargs):
             )
 
             # Verify ASFF was NOT created for non-AWS provider
-            assert (
-                "asff" not in created_writers
-            ), "ASFF writer should NOT be created for non-AWS providers"
+            assert "asff" not in created_writers, (
+                "ASFF writer should NOT be created for non-AWS providers"
+            )
             assert "csv" in created_writers, "CSV writer should be created"
             assert "ocsf" in created_writers, "OCSF writer should be created"
 
@@ -2454,6 +2455,51 @@ def _complete_scan(tenant_id, scan_id, provider_id):
             == 1
         )
 
+    def test_no_op_when_provider_does_not_exist(self, tenants_fixture):
+        """Return None without raising when the provider was already deleted."""
+        tenant = tenants_fixture[0]
+        missing_provider_id = str(uuid.uuid4())
+        task_id = str(uuid.uuid4())
+        self._create_task_result(tenant.id, task_id)
+
+        with (
+            patch("tasks.tasks.perform_prowler_scan") as mock_scan,
+            patch("tasks.tasks._perform_scan_complete_tasks") as mock_complete_tasks,
+            self._override_task_request(perform_scheduled_scan_task, id=task_id),
+        ):
+            result = perform_scheduled_scan_task.run(
+                tenant_id=str(tenant.id), provider_id=missing_provider_id
+            )
+
+        assert result is None
+        mock_scan.assert_not_called()
+        mock_complete_tasks.assert_not_called()
+
+
+@pytest.mark.django_db
+class TestPerformScanTask:
+    """Unit tests for perform_scan_task."""
+
+    def test_no_op_when_provider_does_not_exist(self, tenants_fixture):
+        """Return None without raising when the provider was already deleted."""
+        tenant = tenants_fixture[0]
+        missing_provider_id = str(uuid.uuid4())
+        scan_id = str(uuid.uuid4())
+
+        with (
+            patch("tasks.tasks.perform_prowler_scan") as mock_scan,
+            patch("tasks.tasks._perform_scan_complete_tasks") as mock_complete_tasks,
+        ):
+            result = perform_scan_task.run(
+                tenant_id=str(tenant.id),
+                scan_id=scan_id,
+                provider_id=missing_provider_id,
+            )
+
+        assert result is None
+        mock_scan.assert_not_called()
+        mock_complete_tasks.assert_not_called()
+
 
 @pytest.mark.django_db
 class TestReaggregateAllFindingGroupSummaries: