test: accept stderr in string process adapter

puneetdixit200 · puneetdixit200 · commit 4de94bc0e3ec · 2026-05-24T00:21:37.000+05:30
Match the AutoInterrupt wait signature so diff parser tests can pass preserved stderr through finalize_process.

Assisted-by: OpenAI GPT-5
diff --git a/test/lib/helper.py b/test/lib/helper.py
@@ -90,7 +90,7 @@ def __init__(self, input_string):
         self.stdout = io.BytesIO(input_string)
         self.stderr = io.BytesIO()
 
-    def wait(self):
+    def wait(self, stderr=None):
         return 0
 
     poll = wait
