Add tests for loading of extra config

Prior to a move from 'imp' to 'importlib'.

Author: PeterJCLaw

tests/_demo_extra_config.py

@@ -0,0 +1,7 @@
+from django_lightweight_queue.types import QueueName
+
+LIGHTWEIGHT_QUEUE_BACKEND_OVERRIDES = {
+    QueueName('test-queue'): 'tests.test_extra_config.TestBackend',
+}
+
+LIGHTWEIGHT_QUEUE_REDIS_PASSWORD = 'a very bad password'

tests/_demo_extra_config_falsey.py

@@ -0,0 +1,4 @@
+# Override to falsey values
+LIGHTWEIGHT_QUEUE_REDIS_PASSWORD = None
+
+LIGHTWEIGHT_QUEUE_ATOMIC_JOBS = False

tests/_demo_extra_config_unexpected.py

@@ -0,0 +1,4 @@
+
+LIGHTWEIGHT_QUEUE_REDIS_PASSWORD = 'expected'
+
+NOT_REDIS_PASSWORD = 'unexpected'

tests/test_extra_config.py

@@ -0,0 +1,60 @@
+import importlib
+from typing import Optional
+from pathlib import Path
+
+from django.test import SimpleTestCase
+
+from django_lightweight_queue import app_settings
+from django_lightweight_queue.job import Job
+from django_lightweight_queue.types import QueueName, WorkerNumber
+from django_lightweight_queue.utils import get_backend, load_extra_config
+from django_lightweight_queue.backends.base import BaseBackend
+
+TESTS_DIR = Path(__file__).parent
+
+
+class TestBackend(BaseBackend):
+    def enqueue(self, job: Job, queue: QueueName) -> None:
+        pass
+
+    def dequeue(self, queue: QueueName, worker_num: WorkerNumber, timeout: int) -> Optional[Job]:
+        pass
+
+    def length(self, queue: QueueName) -> int:
+        pass
+
+
+class ExtraConfigTests(SimpleTestCase):
+    def setUp(self) -> None:
+        get_backend.cache_clear()
+        super().setUp()
+
+    def tearDown(self) -> None:
+        importlib.reload(app_settings)
+        get_backend.cache_clear()
+        super().tearDown()
+
+    def test_updates_configuration(self) -> None:
+        load_extra_config(str(TESTS_DIR / '_demo_extra_config.py'))
+
+        backend = get_backend('test-queue')
+        self.assertIsInstance(backend, TestBackend)
+
+        self.assertEqual('a very bad password', app_settings.REDIS_PASSWORD)
+
+    def test_warns_about_unexpected_settings(self) -> None:
+        with self.assertWarnsRegex(Warning, r'Ignoring unexpected setting.+\bNOT_REDIS_PASSWORD\b'):
+            load_extra_config(str(TESTS_DIR / '_demo_extra_config_unexpected.py'))
+
+        self.assertEqual('expected', app_settings.REDIS_PASSWORD)
+
+    def test_updates_configuration_with_falsey_values(self) -> None:
+        load_extra_config(str(TESTS_DIR / '_demo_extra_config.py'))
+        load_extra_config(str(TESTS_DIR / '_demo_extra_config_falsey.py'))
+
+        self.assertIsNone(app_settings.REDIS_PASSWORD)
+        self.assertFalse(app_settings.ATOMIC_JOBS)
+
+    def test_rejects_missing_file(self) -> None:
+        with self.assertRaises(FileNotFoundError):
+            load_extra_config(str(TESTS_DIR / '_no_such_file.py'))