Fix storages deprecation warnings (#372)

* ⚙️ Adds Django 4.2 support and fixes trove classifiers

* :shirts: Runs black on code to make CI happy

* :shirts: Runs isort on code to make CI happy

* 💚 Updates test to match exception copy

* 📝 mirrors old README.rst to make docs work

Not a great solution, but a workaround.

* ⚙️ Adds pip cache support

* 🔥 Removes 4.0 from grid because it's no longer supported

* ⚙️ Updates cache-key

This isn't really used, but I think having caching is a win

* ⚙️ Adds missing file

* 🔥 Removes cache line

* Fix storages deprecation warnings

---------

Co-authored-by: Jeff Triplett <[email protected]>

health_check/storage/backends.py

@@ -1,8 +1,13 @@
 import uuid
 
+import django
 from django.conf import settings
 from django.core.files.base import ContentFile
-from django.core.files.storage import get_storage_class
+
+if django.VERSION >= (4, 2):
+    from django.core.files.storage import InvalidStorageError, storages
+else:
+    from django.core.files.storage import get_storage_class
 
 from health_check.backends import BaseHealthCheckBackend
 from health_check.exceptions import ServiceUnavailable
@@ -22,13 +27,20 @@ class MyStorageHealthCheck(StorageHealthCheck):
     (e.g 'django.core.files.storage.FileSystemStorage') or a Storage instance.
     """
 
+    storage_alias = None
     storage = None
 
     def get_storage(self):
-        if isinstance(self.storage, str):
-            return get_storage_class(self.storage)()
+        if django.VERSION >= (4, 2):
+            try:
+                return storages[self.storage_alias]
+            except InvalidStorageError:
+                return None
         else:
-            return self.storage
+            if isinstance(self.storage, str):
+                return get_storage_class(self.storage)()
+            else:
+                return self.storage
 
     def get_file_name(self):
         return "health_check_storage_test/test-%s.txt" % uuid.uuid4()
@@ -68,4 +80,5 @@ def check_status(self):
 
 
 class DefaultFileStorageHealthCheck(StorageHealthCheck):
+    storage_alias = "default"
     storage = settings.DEFAULT_FILE_STORAGE

tests/test_storage.py

@@ -1,5 +1,7 @@
+import unittest
 from unittest import mock
 
+import django
 from django.core.files.storage import Storage
 from django.test import TestCase
 
@@ -10,6 +12,10 @@
 )
 
 
+class CustomStorage(Storage):
+    pass
+
+
 class MockStorage(Storage):
     """
     A Mock Storage backend used for testing.
@@ -68,6 +74,25 @@ def test_get_storage(self):
         default_storage = DefaultFileStorageHealthCheck()
         self.assertIsInstance(default_storage.get_storage(), Storage)
 
+    @unittest.skipUnless((4, 2) <= django.VERSION < (5, 0), "Only for Django 4.2 - 5.0")
+    def test_get_storage_django_between_42_and_50(self):
+        """Check that the old DEFAULT_FILE_STORAGE setting keeps being supported."""
+        # Note: this test doesn't work on Django<4.2 because the setting value is
+        # evaluated when the class attribute DefaultFileStorageHealthCheck.store is
+        # read, which is at import time, before we can mock the setting.
+        with self.settings(DEFAULT_FILE_STORAGE="tests.test_storage.CustomStorage"):
+            default_storage = DefaultFileStorageHealthCheck()
+            self.assertIsInstance(default_storage.get_storage(), CustomStorage)
+
+    @unittest.skipUnless((4, 2) <= django.VERSION, "Django 4.2+ required")
+    def test_get_storage_django_42_plus(self):
+        """Check that the new STORAGES setting is supported."""
+        with self.settings(
+            STORAGES={"default": {"BACKEND": "tests.test_storage.CustomStorage"}}
+        ):
+            default_storage = DefaultFileStorageHealthCheck()
+            self.assertIsInstance(default_storage.get_storage(), CustomStorage)
+
     @mock.patch(
         "health_check.storage.backends.DefaultFileStorageHealthCheck.storage",
         MockStorage(),
@@ -88,21 +113,45 @@ def test_check_status_working(self):
         ):
             self.assertTrue(default_storage_health.check_status())
 
+    @unittest.skipUnless(django.VERSION <= (4, 1), "Only for Django 4.1 and earlier")
     @mock.patch(
         "health_check.storage.backends.DefaultFileStorageHealthCheck.storage",
         MockStorage(saves=False),
     )
-    def test_file_does_not_exist(self):
+    def test_file_does_not_exist_django_41_earlier(self):
+        """Test check_status raises ServiceUnavailable when file is not saved."""
+        default_storage_health = DefaultFileStorageHealthCheck()
+        with self.assertRaises(ServiceUnavailable):
+            default_storage_health.check_status()
+
+    @unittest.skipUnless((4, 2) <= django.VERSION, "Only for Django 4.2+")
+    @mock.patch(
+        "health_check.storage.backends.storages",
+        {"default": MockStorage(saves=False)},
+    )
+    def test_file_does_not_exist_django_42_plus(self):
         """Test check_status raises ServiceUnavailable when file is not saved."""
         default_storage_health = DefaultFileStorageHealthCheck()
         with self.assertRaises(ServiceUnavailable):
             default_storage_health.check_status()
 
+    @unittest.skipUnless(django.VERSION <= (4, 1), "Only for Django 4.1 and earlier")
     @mock.patch(
         "health_check.storage.backends.DefaultFileStorageHealthCheck.storage",
         MockStorage(deletes=False),
     )
-    def test_file_not_deleted(self):
+    def test_file_not_deleted_django_41_earlier(self):
+        """Test check_status raises ServiceUnavailable when file is not deleted."""
+        default_storage_health = DefaultFileStorageHealthCheck()
+        with self.assertRaises(ServiceUnavailable):
+            default_storage_health.check_status()
+
+    @unittest.skipUnless((4, 2) <= django.VERSION, "Only for Django 4.2+")
+    @mock.patch(
+        "health_check.storage.backends.storages",
+        {"default": MockStorage(deletes=False)},
+    )
+    def test_file_not_deleted_django_42_plus(self):
         """Test check_status raises ServiceUnavailable when file is not deleted."""
         default_storage_health = DefaultFileStorageHealthCheck()
         with self.assertRaises(ServiceUnavailable):