Add a python standard out evaluator

1 files changed, 121 insertions, 0 deletions

diff --git a/yaksh/tester/python/verifier.py b/yaksh/tester/python/verifier.py
new file mode 100644
index 0000000..102dcb9
--- /dev/null
+++ b/yaksh/tester/python/verifier.py
@@ -0,0 +1,121 @@
+import sys
+from .utils import import_by_path
+from contextlib import contextmanager
+
+
+@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
+
+# def redirect_stdout():
+#     # import sys
+#     from StringIO import StringIO
+#     oldout,olderr = sys.stdout, sys.stderr
+#     try:
+#         out = StringIO()
+#         err = StringIO()
+#         # sys.stdout,sys.stderr = out, err
+#         yield out, err
+#     finally:
+#         sys.stdout,sys.stderr = oldout, olderr
+#         out = out.getvalue()
+#         err = err.getvalue()
+
+TESTER_BACKEND = {
+    "python": "PythonPrintTesterBackend" #@@@rename to test-case-creator, this file should be backend.py
+}
+
+class TesterException(Exception):
+    """ Parental class for all tester exceptions """
+    pass
+
+class UnknownBackendException(TesterException):
+    """ Exception thrown if tester backend is not recognized. """
+    pass
+
+
+def detect_backend(language):
+    """
+    Detect the right backend for a test case.
+    """
+    backend_name = TESTER_BACKEND.get(language)
+    # backend = import_by_path(backend_name)
+    backend = PythonTesterBackend() #@@@
+    return backend
+
+class PythonPrintTesterBackend(object):
+    def test_code(self, submitted, reference_output):
+        """
+        create a test command
+        """
+        with redirect_stdout() as output_buffer: 
+            g = {}
+            exec submitted in g
+
+        # return_buffer = out.encode('string_escape')
+        raw_output_value = output_buffer.getvalue()
+        output_value = raw_output_value.encode('string_escape').strip()
+        if output_value == str(reference_output):
+            return True
+        else:
+            raise ValueError("Incorrect Answer", output_value, reference_output)
+
+
+class PythonTesterBackend(object):
+    # def __init__(self, test_case):
+    #     self._test_case = test_case
+    def create(self): #@@@ test()
+        """
+        create a test command
+        """
+        test_code = "assert {0}({1}) == {2}".format(self.test_case_parameters['function_name'], self.test_case_parameters['args'],
+                                     self.test_case_parameters['expected_answer'])
+        return test_code
+
+    def pack(self, test_case):
+        kw_args_dict = {}
+        pos_args_list = []
+        test_case_data = {}
+        test_case_data['test_id'] = test_case.id
+        test_case_data['func_name'] = test_case.func_name
+        test_case_data['expected_answer'] = test_case.expected_answer
+
+        if test_case.kw_args:
+            for args in test_case.kw_args.split(","):
+                arg_name, arg_value = args.split("=")
+                kw_args_dict[arg_name.strip()] = arg_value.strip()
+
+        if test_case.pos_args:
+            for args in test_case.pos_args.split(","):
+                pos_args_list.append(args.strip())
+
+        test_case_data['kw_args'] = kw_args_dict
+        test_case_data['pos_args'] = pos_args_list
+
+        return test_case_data
+
+    def unpack(self, test_case_data):
+        pos_args = ", ".join(str(i) for i in test_case_data.get('pos_args')) \
+                            if test_case_data.get('pos_args') else ""
+        kw_args = ", ".join(str(k+"="+a) for k, a
+                         in test_case_data.get('kw_args').iteritems()) \
+                        if test_case_data.get('kw_args') else ""
+        args = pos_args + ", " + kw_args if pos_args and kw_args \
+                                            else pos_args or kw_args
+        function_name = test_case_data.get('func_name')
+        expected_answer = test_case_data.get('expected_answer')
+
+        self.test_case_parameters = {
+            'args': args,
+            'function_name': function_name,
+            'expected_answer': expected_answer
+        }
+
+        return self.test_case_parameters
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