Reworked the detection of local storages for the collectstatic command.

Before 4befb30 the detection was broken because we used isinstance
against a LazyObject rather than against a Storage class. That commit
fixed it by looking directly at the object wrapped by LazyObject.
This could however be a problem to anyone who subclasses the
collectstatic management Command and directly supplies a Storage class.

Refs #21581.

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/staticfiles_tests/tests.py b/tests/staticfiles_tests/tests.py
index e72875566b..21ecf84bbc 100644
--- a/tests/staticfiles_tests/tests.py
+++ b/tests/staticfiles_tests/tests.py
@@ -23,6 +23,9 @@ from django.utils import six
 from django.contrib.staticfiles import finders, storage
 from django.contrib.staticfiles.management.commands import collectstatic
 
+from .storage import DummyStorage
+
+
 TEST_ROOT = os.path.dirname(upath(__file__))
 TEST_SETTINGS = {
     'DEBUG': True,
@@ -263,6 +266,29 @@ class TestConfiguration(StaticFilesTestCase):
                         'without having set the STATIC_ROOT setting to a filesystem path'):
                     call_command('collectstatic', interactive=False, verbosity=0, stderr=err)
 
+    def test_local_storage_detection_helper(self):
+        staticfiles_storage = storage.staticfiles_storage
+        try:
+            storage.staticfiles_storage._wrapped = empty
+            with override_settings(STATICFILES_STORAGE='django.contrib.staticfiles.storage.StaticFilesStorage'):
+                command = collectstatic.Command()
+                self.assertTrue(command.is_local_storage())
+
+            storage.staticfiles_storage._wrapped = empty
+            with override_settings(STATICFILES_STORAGE='staticfiles_tests.storage.DummyStorage'):
+                command = collectstatic.Command()
+                self.assertFalse(command.is_local_storage())
+
+            storage.staticfiles_storage = storage.FileSystemStorage()
+            command = collectstatic.Command()
+            self.assertTrue(command.is_local_storage())
+
+            storage.staticfiles_storage = DummyStorage()
+            command = collectstatic.Command()
+            self.assertFalse(command.is_local_storage())
+        finally:
+            storage.staticfiles_storage = staticfiles_storage
+
 
 class TestCollection(CollectionTestCase, TestDefaults):
     """