#99 use contextmanager decorator from contextlib instead of verbose c…

…lass + some annotations

tests/management_command_test.py

@@ -1,3 +1,5 @@
+from collections.abc import Generator
+from contextlib import contextmanager
 from io import BytesIO
 
 import pytest
@@ -21,32 +23,25 @@ def test_media_backup_with_wrong_django_version(mocker):
 
 
 class StubStorage:
-    def __init__(self):
-        self._files = []
+    def __init__(self) -> None:
+        self._files: dict[str, str] = {}
 
-    def exists(self, path):
+    def exists(self, path: str) -> bool:
         return path in self._files
 
-    def save(self, name, _content):
-        self._files.append(name)
+    def save(self, name: str, content: str) -> None:
+        self._files[name] = content
 
-    @staticmethod
-    def open(name, _mode):
-        class StubFile:
-            def __init__(self, file_name):
-                self.name = file_name
-
-            def __enter__(self):
-                return self
-
-            def __exit__(self, *args):
-                pass
-
-        return StubFile(name)
-
-    def listdir(self, _path):
+    def listdir(self, _path: str) -> tuple[list, dict[str, str]]:
         return [], self._files
 
+    @contextmanager
+    def open(self, name: str, _mode: str) -> Generator[str, None, None]:
+        try:
+            yield self._files[name]
+        finally:
+            pass
+
 
 @pytest.fixture
 def stub_storages(settings):