1 files changed, 10 insertions, 0 deletions
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index 63435780c9..9afa282b69 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -1681,6 +1681,16 @@ def patch(test_instance, object_to_patch, attr_name, new_value):
     setattr(object_to_patch, attr_name, new_value)
 
 
+@contextlib.contextmanager
+def patch_list(orig):
+    """Like unittest.mock.patch.dict, but for lists."""
+    try:
+        saved = orig[:]
+        yield
+    finally:
+        orig[:] = saved
+
+
 def run_in_subinterp(code):
     """
     Run code in a subinterpreter. Raise unittest.SkipTest if the tracemalloc