tests: clear instance cache of cached filesystems between tests

Author: ap--

fsspec/tests/test_core.py

@@ -20,6 +20,19 @@
 )
 
 
+@pytest.fixture(scope="function", autouse=True)
+def clear_cachingfilesystem_instance_caches():
+    # prevent test cross-contamination due to cached fs instances
+    from fsspec.implementations.cached import CachingFileSystem
+
+    classes = [CachingFileSystem]
+    while classes:
+        cls = classes.pop()
+        cls.clear_instance_cache()
+        classes.extend(cls.__subclasses__())
+    yield
+
+
 @contextmanager
 def tempzip(data=None):
     data = data or {}