[Fix] Add custom mock for sys.stdin that supports buffer attribute in LCBV6 (#2393)

* fix

* fix

* fix lint

Author: Myhs-phz

opencompass/datasets/livecodebench/testing_util.py

@@ -1,3 +1,4 @@
+# flake8: noqa
 # Copyright LiveCodeBench @ 2024,
 
 import ast
@@ -657,18 +658,55 @@ def stripped_string_compare(s1, s2):
     return s1 == s2
 
 
+class MockStdinWithBuffer:
+
+    def __init__(self, inputs: str):
+        self.inputs = inputs
+        self._stringio = StringIO(inputs)
+        self.buffer = MockBuffer(inputs)
+
+    def read(self, *args):
+        return self.inputs
+
+    def readline(self, *args):
+        return self._stringio.readline(*args)
+
+    def readlines(self, *args):
+        return self.inputs.split('\n')
+
+    def __getattr__(self, name):
+        # Delegate other attributes to StringIO
+        return getattr(self._stringio, name)
+
+
+class MockBuffer:
+
+    def __init__(self, inputs: str):
+        self.inputs = inputs.encode('utf-8')  # Convert to bytes
+
+    def read(self, *args):
+        # Return as byte strings that can be split
+        return self.inputs
+
+    def readline(self, *args):
+        return self.inputs.split(b'\n')[0] + b'\n'
+
+
 def call_method(method, inputs):
 
     if isinstance(inputs, list):
         inputs = '\n'.join(inputs)
 
     inputs_line_iterator = iter(inputs.split('\n'))
 
+    # Create custom stdin mock with buffer support
+    mock_stdin = MockStdinWithBuffer(inputs)
+
     # sys.setrecursionlimit(10000)
 
     # @patch('builtins.input', side_effect=inputs.split("\n"))
     @patch('builtins.open', mock_open(read_data=inputs))
-    @patch('sys.stdin', StringIO(inputs))
+    @patch('sys.stdin', mock_stdin)  # Use our custom mock instead of StringIO
     @patch('sys.stdin.readline', lambda *args: next(inputs_line_iterator))
     @patch('sys.stdin.readlines', lambda *args: inputs.split('\n'))
     @patch('sys.stdin.read', lambda *args: inputs)