Add a python standard out evaluator

1 files changed, 47 insertions, 0 deletions

diff --git a/yaksh/python_stdout_evaluator.py b/yaksh/python_stdout_evaluator.py
new file mode 100644
index 0000000..89d3424
--- /dev/null
+++ b/yaksh/python_stdout_evaluator.py
@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+import sys
+import traceback
+import os
+from os.path import join
+import importlib
+from contextlib import contextmanager
+
+# local imports
+from code_evaluator import CodeEvaluator
+
+
+@contextmanager
+def redirect_stdout():
+        from StringIO import StringIO
+        new_target = StringIO()
+
+        old_target, sys.stdout = sys.stdout, new_target # replace sys.stdout
+        try:
+            yield new_target # run some code with the replaced stdout
+        finally:
+            sys.stdout = old_target # restore to the previous value
+
+
+class PythonStdoutEvaluator(CodeEvaluator):
+    """Tests the Python code obtained from Code Server"""
+
+    def check_code(self, test, user_answer, ref_code_path):
+        success = False
+
+        try:
+            tb = None
+            test_code = test
+            submitted = compile(user_answer, '<string>', mode='exec')
+            with redirect_stdout() as output_buffer: 
+                g = {}
+                exec submitted in g
+            raw_output_value = output_buffer.getvalue()
+            output_value = raw_output_value.encode('string_escape').strip()
+            if output_value == str(test_code):
+                success = True
+                err = 'Correct answer'
+            else:
+                raise ValueError("Incorrect Answer")
+
+        del tb
+        return success, err
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