Merge pull request #471 from adityacp/fix_error_messages

Python Assertion Evaluation additions and changes

7 files changed, 359 insertions, 324 deletions

diff --git a/yaksh/error_messages.py b/yaksh/error_messages.py
index 7ea8618..7a18c22 100644
--- a/yaksh/error_messages.py
+++ b/yaksh/error_messages.py
@@ -3,7 +3,9 @@ try:
 except ImportError:
     from itertools import izip_longest as zip_longest
 
-def prettify_exceptions(exception, message, traceback=None, testcase=None):
+
+def prettify_exceptions(exception, message, traceback=None,
+                        testcase=None, line_no=None):
     err = {"type": "assertion",
            "exception": exception,
            "traceback": traceback,
@@ -13,23 +15,28 @@ def prettify_exceptions(exception, message, traceback=None, testcase=None):
         err["traceback"] = None
 
     if exception == 'AssertionError':
-        value = ("Expected answer from the"  
-                + " test case did not match the output")
-        err["message"] = value
+        value = ("Expected answer from the" +
+                 " test case did not match the output")
+        if message:
+            err["message"] = message
+        else:
+            err["message"] = value
         err["traceback"] = None
-        if testcase:
-            err["test_case"] = testcase
+    err["test_case"] = testcase
+    err["line_no"] = line_no
     return err
 
+
 def _get_incorrect_user_lines(exp_lines, user_lines):
     err_line_numbers = []
     for line_no, (expected_line, user_line) in \
-     enumerate(zip_longest(exp_lines, user_lines)):
-        if not user_line or not expected_line or \
-         user_line.strip() != expected_line.strip():
+            enumerate(zip_longest(exp_lines, user_lines)):
+        if (not user_line or not expected_line or
+                user_line.strip() != expected_line.strip()):
             err_line_numbers.append(line_no)
     return err_line_numbers
-    
+
+
 def compare_outputs(expected_output, user_output, given_input=None):
     given_lines = user_output.splitlines()
     exp_lines = expected_output.splitlines()
@@ -44,18 +51,17 @@ def compare_outputs(expected_output, user_output, given_input=None):
     msg["error_line_numbers"] = err_line_numbers
     if ng != ne:
         msg["error_msg"] = ("Incorrect Answer: "
-                            + "We had expected {} number of lines. "\
-                                .format(ne)
+                            + "We had expected {} number of lines. ".format(ne)
                             + "We got {} number of lines.".format(ng)
                             )
         return False, msg
     else:
         if err_line_numbers:
             msg["error_msg"] = ("Incorrect Answer: "
-                             + "Line number(s) {0} did not match."
-                                .format(", ".join(map(
-                                  str,[x+1 for x in err_line_numbers]
-                                ))))
+                                + "Line number(s) {0} did not match."
+                                .format(", ".join(
+                                    map(str, [x+1 for x in err_line_numbers])
+                                )))
             return False, msg
         else:
             msg["error_msg"] = "Correct Answer"
diff --git a/yaksh/evaluator_tests/test_python_evaluation.py b/yaksh/evaluator_tests/test_python_evaluation.py
index 71d7732..1933d17 100644
--- a/yaksh/evaluator_tests/test_python_evaluation.py
+++ b/yaksh/evaluator_tests/test_python_evaluation.py
@@ -1,7 +1,6 @@
 from __future__ import unicode_literals
 import unittest
 import os
-import sys
 import tempfile
 import shutil
 from textwrap import dedent
@@ -26,13 +25,13 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
         self.in_dir = tmp_in_dir_path
         self.test_case_data = [{"test_case_type": "standardtestcase",
                                 "test_case": 'assert(add(1,2)==3)',
-                                 'weight': 0.0},
+                                'weight': 0.0},
                                {"test_case_type": "standardtestcase",
                                 "test_case": 'assert(add(-1,2)==1)',
-                                 'weight': 0.0},
+                                'weight': 0.0},
                                {"test_case_type": "standardtestcase",
                                 "test_case":  'assert(add(-1,-2)==-3)',
-                                 'weight': 0.0},
+                                'weight': 0.0},
                                ]
         self.timeout_msg = ("Code took more than {0} seconds to run. "
                             "You probably have an infinite loop in"
@@ -46,14 +45,12 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
     def test_correct_answer(self):
         # Given
         user_answer = "def add(a,b):\n\treturn a + b"
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
                   }
 
         # When
@@ -66,14 +63,12 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
     def test_incorrect_answer(self):
         # Given
         user_answer = "def add(a,b):\n\treturn a - b"
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
                   }
 
         # When
@@ -85,13 +80,13 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
         given_test_case_list = [tc["test_case"] for tc in self.test_case_data]
         for error in result.get("error"):
             self.assertEqual(error['exception'], 'AssertionError')
-            self.assertEqual(error['message'],
-                 "Expected answer from the test case did not match the output"
-                 )
+            self.assertEqual(
+                error['message'],
+                "Expected answer from the test case did not match the output"
+                )
         error_testcase_list = [tc['test_case'] for tc in result.get('error')]
         self.assertEqual(error_testcase_list, given_test_case_list)
 
-
     def test_partial_incorrect_answer(self):
         # Given
         user_answer = "def add(a,b):\n\treturn abs(a) + abs(b)"
@@ -100,19 +95,17 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                            'weight': 1.0},
                           {"test_case_type": "standardtestcase",
                            "test_case":  'assert(add(-1,-2)==-3)',
-                            'weight': 1.0},
+                           'weight': 1.0},
                           {"test_case_type": "standardtestcase",
                            "test_case": 'assert(add(1,2)==3)',
                            'weight': 2.0}
                           ]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': True,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': True,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
                   }
 
         # When
@@ -126,22 +119,22 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
         given_test_case_list.remove('assert(add(1,2)==3)')
         for error in result.get("error"):
             self.assertEqual(error['exception'], 'AssertionError')
-            self.assertEqual(error['message'],
-                 "Expected answer from the test case did not match the output"
-                 )
+            self.assertEqual(
+                error['message'],
+                "Expected answer from the test case did not match the output"
+                )
         error_testcase_list = [tc['test_case'] for tc in result.get('error')]
         self.assertEqual(error_testcase_list, given_test_case_list)
+
     def test_infinite_loop(self):
         # Given
         user_answer = "def add(a, b):\n\twhile True:\n\t\tpass"
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
                   }
 
         # When
@@ -168,14 +161,12 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                             "SyntaxError",
                             "invalid syntax"
                             ]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
                   }
 
         # When
@@ -201,14 +192,12 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                             "IndentationError",
                             "indented block"
                             ]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
                   }
 
         # When
@@ -220,9 +209,9 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
         self.assertFalse(result.get("success"))
         self.assertEqual(5, len(err))
         for msg in indent_error_msg:
-            self.assert_correct_output(msg, 
-                                      result.get("error")[0]['traceback']
-                                      )
+            self.assert_correct_output(
+                msg, result.get("error")[0]['traceback']
+            )
 
     def test_name_error(self):
         # Given
@@ -234,15 +223,13 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                           "defined"
                           ]
 
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
-                }
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -258,15 +245,13 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
             return add(3, 3)
         """)
         recursion_error_msg = "maximum recursion depth exceeded"
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
-                }
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -289,15 +274,13 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                           "argument"
                           ]
 
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
-                }
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -323,25 +306,26 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                            "base"
                            ]
 
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
-                }
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
+                  }
 
         # When
         grader = Grader(self.in_dir)
         result = grader.evaluate(kwargs)
-        err = result.get("error")[0]['traceback']
+        errors = result.get("error")
 
         # Then
         self.assertFalse(result.get("success"))
         for msg in value_error_msg:
-            self.assert_correct_output(msg, err)
+            self.assert_correct_output(msg, errors[0]['traceback'])
+        for index, error in enumerate(errors):
+            self.assertEqual(error['test_case'],
+                             self.test_case_data[index]['test_case'])
 
     def test_file_based_assert(self):
         # Given
@@ -356,15 +340,13 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                     return f.read()[0]
             """)
 
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data,
-                }
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data,
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -390,25 +372,23 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                             ]
 
         kwargs = {'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
-                }
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
+                  }
 
         # When
         grader = Grader(self.in_dir)
         result = grader.evaluate(kwargs)
-        err =  result.get("error")[0]['traceback']
+        err = result.get("error")[0]['traceback']
 
         # Then
         self.assertFalse(result.get("success"))
         for msg in syntax_error_msg:
             self.assert_correct_output(msg, err)
 
-
     def test_multiple_testcase_error(self):
         """ Tests the user answer with an correct test case
          first and then with an incorrect test case """
@@ -418,7 +398,8 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                            "test_case": 'assert(palindrome("abba")==True)',
                            "weight": 0.0},
                           {"test_case_type": "standardtestcase",
-                           "test_case": 's="abbb"\nassert palindrome(S)==False',
+                           "test_case": 's="abbb"\n'
+                                        'assert palindrome(S)==False',
                            "weight": 0.0}
                           ]
         name_error_msg = ["Traceback",
@@ -426,15 +407,13 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                           "NameError",
                           "name 'S' is not defined"
                           ]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
-                }
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -454,18 +433,15 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
                                 return type(a)
                             """)
         test_case_data = [{"test_case_type": "standardtestcase",
-                             "test_case": 'assert(strchar("hello")==str)',
-                             "weight": 0.0
-                            },]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
-                }
+                           "test_case": 'assert(strchar("hello")==str)',
+                           "weight": 0.0}]
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
+                  }
         # When
         grader = Grader(self.in_dir)
         result = grader.evaluate(kwargs)
@@ -473,6 +449,31 @@ class PythonAssertionEvaluationTestCases(EvaluatorBaseTest):
         # Then
         self.assertTrue(result.get("success"))
 
+    def test_incorrect_answer_with_nose_assert(self):
+        user_answer = dedent("""\
+                             def add(a, b):
+                                return a - b
+                            """)
+        test_case_data = [{"test_case_type": "standardtestcase",
+                           "test_case": 'assert_equal(add(1, 2), 3)',
+                           "weight": 0.0}]
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
+                  }
+        # When
+        grader = Grader(self.in_dir)
+        result = grader.evaluate(kwargs)
+
+        # Then
+        self.assertFalse(result.get("success"))
+        error = result.get("error")[0]
+        self.assertEqual(error['exception'], 'AssertionError')
+        self.assertEqual(error['message'], '-1 != 3')
+
 
 class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
     def setUp(self):
@@ -501,13 +502,12 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
                              """
                              )
         kwargs = {'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data
-                }
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -534,13 +534,12 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
                              )
 
         kwargs = {'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data
-                }
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -551,11 +550,13 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
 
     def test_correct_answer_string(self):
         # Given
-        self.test_case_data = [{"test_case_type": "stdiobasedtestcase",
-                                "expected_input": ("the quick brown fox jumps over the lazy dog\nthe"),
-                                "expected_output": "2",
-                                "weight": 0.0
-                                }]
+        self.test_case_data = [{
+            "test_case_type": "stdiobasedtestcase",
+            "expected_input": ("the quick brown fox jumps over "
+                               "the lazy dog\nthe"),
+            "expected_output": "2",
+            "weight": 0.0
+            }]
         user_answer = dedent("""
                                 from six.moves import input
                                 a = str(input())
@@ -565,13 +566,12 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
                              )
 
         kwargs = {'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data
-                }
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -594,13 +594,12 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
                              """
                              )
         kwargs = {'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data
-                }
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -629,13 +628,12 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
                              """
                              )
         kwargs = {'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data
-                }
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -646,24 +644,24 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
 
     def test_infinite_loop(self):
         # Given
-        self.test_case_data = [{"test_case_type": "stdiobasedtestcase",
-                            "expected_input": "1\n2",
-                            "expected_output": "3",
-                            "weight": 0.0
-                            }]
+        self.test_case_data = [{
+            "test_case_type": "stdiobasedtestcase",
+            "expected_input": "1\n2",
+            "expected_output": "3",
+            "weight": 0.0
+            }]
         timeout_msg = ("Code took more than {0} seconds to run. "
-                            "You probably have an infinite loop in"
-                            " your code.").format(SERVER_TIMEOUT)
+                       "You probably have an infinite loop in"
+                       " your code.").format(SERVER_TIMEOUT)
         user_answer = "while True:\n\tpass"
 
         kwargs = {'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': self.test_case_data
-                }
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': self.test_case_data
+                  }
 
         # When
         grader = Grader(self.in_dir)
@@ -675,7 +673,6 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
                                    )
         self.assertFalse(result.get('success'))
 
-
     def test_unicode_literal_bug(self):
         # Given
         user_answer = dedent("""\
@@ -687,21 +684,44 @@ class PythonStdIOEvaluationTestCases(EvaluatorBaseTest):
                            "expected_output": "str",
                            "weight": 0.0
                            }]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
-                }
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
+                  }
         # When
         grader = Grader(self.in_dir)
         result = grader.evaluate(kwargs)
         # Then
         self.assertTrue(result.get("success"))
 
+    def test_get_error_lineno(self):
+        user_answer = dedent("""\
+                             print(1/0)
+                            """)
+        test_case_data = [{"test_case_type": "stdiobasedtestcase",
+                           "expected_input": "",
+                           "expected_output": "1",
+                           "weight": 0.0
+                           }]
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
+                  }
+        # When
+        grader = Grader(self.in_dir)
+        result = grader.evaluate(kwargs)
+        # Then
+        self.assertFalse(result.get("success"))
+        error = result.get("error")[0]
+        self.assertEqual(error['line_no'], 1)
+        self.assertEqual(error['exception'], "ZeroDivisionError")
+
 
 class PythonHookEvaluationTestCases(EvaluatorBaseTest):
 
@@ -733,19 +753,17 @@ class PythonHookEvaluationTestCases(EvaluatorBaseTest):
                                     success, err, mark_fraction = True, "", 1.0
                                 return success, err, mark_fraction
                             """
-                            )
+                           )
 
         test_case_data = [{"test_case_type": "hooktestcase",
-                           "hook_code": hook_code,"weight": 1.0
-                            }]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': True,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
+                           "hook_code": hook_code, "weight": 1.0
+                           }]
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': True,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
                   }
 
         # When
@@ -768,20 +786,18 @@ class PythonHookEvaluationTestCases(EvaluatorBaseTest):
                                     success, err, mark_fraction = True, "", 1.0
                                 return success, err, mark_fraction
                             """
-                            )
+                           )
 
         test_case_data = [{"test_case_type": "hooktestcase",
-                           "hook_code": hook_code,"weight": 1.0
-                            }]
-
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
+                           "hook_code": hook_code, "weight": 1.0
+                           }]
+
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
                   }
 
         # When
@@ -805,21 +821,19 @@ class PythonHookEvaluationTestCases(EvaluatorBaseTest):
                                     success, err, mark_fraction = True, "", 1.0
                                 return success, err, mark_fraction
                             """
-                            )
+                           )
 
         test_case_data = [{"test_case_type": "standardtestcase",
                            "test_case": assert_test_case, 'weight': 1.0},
                           {"test_case_type": "hooktestcase",
                            "hook_code": hook_code, 'weight': 1.0},
                           ]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': True,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': True,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
                   }
 
         # When
@@ -842,7 +856,7 @@ class PythonHookEvaluationTestCases(EvaluatorBaseTest):
                                     success, err, mark_fraction = True, "", 0.5
                                 return success, err, mark_fraction
                             """
-                            )
+                             )
         hook_code_2 = dedent("""\
                             def check_answer(user_answer):
                                 success = False
@@ -853,22 +867,19 @@ class PythonHookEvaluationTestCases(EvaluatorBaseTest):
                                     success, err, mark_fraction = True, "", 1.0
                                 return success, err, mark_fraction
                             """
-                            )
-
+                             )
 
         test_case_data = [{"test_case_type": "hooktestcase",
                            "hook_code": hook_code_1, 'weight': 1.0},
                           {"test_case_type": "hooktestcase",
                            "hook_code": hook_code_2, 'weight': 1.0},
                           ]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': True,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': True,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
                   }
 
         # When
@@ -892,19 +903,18 @@ class PythonHookEvaluationTestCases(EvaluatorBaseTest):
                                     success, err, mark_fraction = True, "", 1.0
                                 return success, err, mark_fraction
                             """
-                            )
+                           )
+
         test_case_data = [{"test_case_type": "hooktestcase",
-                           "hook_code": hook_code,"weight": 1.0
-                            }]
-
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
+                           "hook_code": hook_code, "weight": 1.0
+                           }]
+
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
                   }
 
         # When
@@ -931,19 +941,18 @@ class PythonHookEvaluationTestCases(EvaluatorBaseTest):
                                     success, err, mark_fraction = True, "", 1.0
                                 return success, err, mark_fraction
                             """
-                            )
+                           )
+
         test_case_data = [{"test_case_type": "hooktestcase",
-                           "hook_code": hook_code,"weight": 1.0
-                            }]
-        kwargs = {
-                  'metadata': {
-                    'user_answer': user_answer,
-                    'file_paths': self.file_paths,
-                    'assign_files': [(self.tmp_file, False)],
-                    'partial_grading': False,
-                    'language': 'python'
-                    },
-                    'test_case_data': test_case_data,
+                           "hook_code": hook_code, "weight": 1.0
+                           }]
+        kwargs = {'metadata': {
+                  'user_answer': user_answer,
+                  'file_paths': self.file_paths,
+                  'assign_files': [(self.tmp_file, False)],
+                  'partial_grading': False,
+                  'language': 'python'},
+                  'test_case_data': test_case_data,
                   }
 
         # When
@@ -953,5 +962,6 @@ class PythonHookEvaluationTestCases(EvaluatorBaseTest):
         # Then
         self.assertTrue(result.get('success'))
 
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/yaksh/grader.py b/yaksh/grader.py
index c9dc8a2..320e7e7 100644
--- a/yaksh/grader.py
+++ b/yaksh/grader.py
@@ -1,22 +1,12 @@
 #!/usr/bin/env python
 from __future__ import unicode_literals
 import sys
-import pwd
 import os
-import stat
 import contextlib
-from os.path import isdir, dirname, abspath, join, isfile, exists
+from os.path import dirname, abspath
 import signal
 import traceback
-from multiprocessing import Process, Queue
-import subprocess
-import re
 
-try:
-    from SimpleXMLRPCServer import SimpleXMLRPCServer
-except ImportError:
-    # The above import will not work on Python-3.x.
-    from xmlrpc.server import SimpleXMLRPCServer
 
 # Local imports
 from .settings import SERVER_TIMEOUT
@@ -26,11 +16,13 @@ from .error_messages import prettify_exceptions
 MY_DIR = abspath(dirname(__file__))
 registry = None
 
+
 # Raised when the code times-out.
 # c.f. http://pguides.net/python/timeout-a-function
 class TimeoutException(Exception):
     pass
 
+
 @contextlib.contextmanager
 def change_dir(path):
     cur_dir = abspath(dirname(MY_DIR))
@@ -75,7 +67,6 @@ class Grader(object):
         self.timeout_msg = msg
         self.in_dir = in_dir if in_dir else MY_DIR
 
-
     def evaluate(self, kwargs):
         """Evaluates given code with the test cases based on
         given arguments in test_case_data.
@@ -122,7 +113,6 @@ class Grader(object):
             test_case_instances.append(test_case_instance)
         return test_case_instances
 
-
     def safe_evaluate(self, test_case_instances):
         """
         Handles code evaluation along with compilation, signal handling
@@ -157,20 +147,24 @@ class Grader(object):
                 test_case_instance.teardown()
 
         except TimeoutException:
-            error.append(prettify_exceptions("TimeoutException",
-                                             self.timeout_msg
-                                             )
-                         )
-        except Exception:
+            error.append(
+                prettify_exceptions("TimeoutException", self.timeout_msg)
+                )
+        except Exception as e:
             exc_type, exc_value, exc_tb = sys.exc_info()
             tb_list = traceback.format_exception(exc_type, exc_value, exc_tb)
+            try:
+                line_no = e.lineno
+            except AttributeError:
+                line_no = traceback.extract_tb(exc_tb)[-1][1]
             if len(tb_list) > 2:
                 del tb_list[1:3]
-            error.append(prettify_exceptions(exc_type.__name__,
-                                         str(exc_value),
-                                         "".join(tb_list),
-                                         )
-                         )
+            error.append(
+                prettify_exceptions(
+                    exc_type.__name__, str(exc_value), "".join(tb_list),
+                    line_no=line_no
+                    )
+                )
         finally:
             # Set back any original signal handler.
             set_original_signal_handler(prev_handler)
diff --git a/yaksh/python_assertion_evaluator.py b/yaksh/python_assertion_evaluator.py
index 440f422..4b016a1 100644
--- a/yaksh/python_assertion_evaluator.py
+++ b/yaksh/python_assertion_evaluator.py
@@ -1,10 +1,6 @@
 #!/usr/bin/env python
 import sys
 import traceback
-import os
-import re
-from os.path import join
-import importlib
 
 # Local imports
 from .file_utils import copy_files, delete_files
@@ -53,22 +49,24 @@ class PythonAssertionEvaluator(BaseEvaluator):
         --------
         Returns a tuple (success, error, test_case_weight)
 
-        success - Boolean, indicating if code was executed successfully, correctly
+        success - Boolean, indicating if code was executed successfully,
+        correctly
         weight - Float, indicating total weight of all successful test cases
         error - String, error message if success is false
 
-        returns (True, "Correct answer", 1.0) : If the student script passes all
-        test cases/have same output, when compared to the instructor script
+        returns (True, "Correct answer", 1.0) : If the student script passes
+        all test cases/have same output, when compared to the instructor script
 
         returns (False, error_msg, 0.0): If the student script fails a single
         test/have dissimilar output, when compared to the instructor script.
 
-        Returns (False, error_msg, 0.0): If mandatory arguments are not files or if
-        the required permissions are not given to the file(s).
+        Returns (False, error_msg, 0.0): If mandatory arguments are not files
+        or if the required permissions are not given to the file(s).
         """
         success = False
         mark_fraction = 0.0
         try:
+            exec("from nose.tools import *", self.exec_scope)
             _tests = compile(self.test_case, '<string>', mode='exec')
             exec(_tests, self.exec_scope)
         except TimeoutException:
@@ -76,12 +74,14 @@ class PythonAssertionEvaluator(BaseEvaluator):
         except Exception:
             exc_type, exc_value, exc_tb = sys.exc_info()
             tb_list = traceback.format_exception(exc_type, exc_value, exc_tb)
+            line_no = traceback.extract_tb(exc_tb)[-1][1]
             if len(tb_list) > 2:
                 del tb_list[1:3]
             err = prettify_exceptions(exc_type.__name__,
                                       str(exc_value),
                                       "".join(tb_list),
-                                      self.test_case
+                                      self.test_case,
+                                      line_no
                                       )
         else:
             success = True
diff --git a/yaksh/static/yaksh/js/requesthandler.js b/yaksh/static/yaksh/js/requesthandler.js
index a215ce4..952de3a 100644
--- a/yaksh/static/yaksh/js/requesthandler.js
+++ b/yaksh/static/yaksh/js/requesthandler.js
@@ -75,6 +75,24 @@ function response_handler(method_type, content_type, data, uid){
           var error_output = document.getElementById("error_panel");
           error_output.innerHTML = res.error;
           focus_on_error(error_output);
+          if(global_editor.editor){
+            err_lineno = $("#err_lineno").val();
+            if(marker){
+              marker.clear();
+            }
+            if(err_lineno){
+              var lineno = parseInt(err_lineno) - 1;
+              var editor = global_editor.editor;
+              var line_length = editor.getLine(lineno).length;
+              marker = editor.markText({line: lineno, ch: 0}, {line: lineno, ch: line_length},
+                                       {className: "activeline", clearOnEnter:true});
+              }
+            else{
+              if(marker){
+                marker.clear();
+              }
+            }
+          }
         }
     } else {
         reset_values();
@@ -125,6 +143,8 @@ function ajax_check_code(url, method_type, data_type, data, uid)
 
 var global_editor = {};
 var csrftoken = jQuery("[name=csrfmiddlewaretoken]").val();
+var err_lineno;
+var marker;
 $(document).ready(function(){
   if(is_exercise == "True" && can_skip == "False"){
       setTimeout(function() {show_solution();}, delay_time*1000);
@@ -148,6 +168,7 @@ $(document).ready(function(){
       mode: mode_dict[lang],
       gutter: true,
       lineNumbers: true,
+      styleSelectedText: true,
       onChange: function (instance, changes) {
           render();
       }
diff --git a/yaksh/templates/yaksh/error_template.html b/yaksh/templates/yaksh/error_template.html
index 61657ae..301020e 100644
--- a/yaksh/templates/yaksh/error_template.html
+++ b/yaksh/templates/yaksh/error_template.html
@@ -3,7 +3,6 @@
 {% endblock %}
 
 {% load custom_filters %}
-
 {% if error_message %}
     {% for error in error_message %}
 
@@ -35,6 +34,7 @@
           </tr>
           <tr>
             {% if error.traceback %}
+            <input type="hidden" id="err_lineno" value="{{error.line_no}}">
             <td><b>Full Traceback: </b></td>
             <td><pre>{{error.traceback}}</pre></td>
             {% endif %}
diff --git a/yaksh/templates/yaksh/question.html b/yaksh/templates/yaksh/question.html
index b65073a..ebfe066 100644
--- a/yaksh/templates/yaksh/question.html
+++ b/yaksh/templates/yaksh/question.html
@@ -11,6 +11,10 @@
     .CodeMirror{
         border-style: groove;
     }
+    .activeline {
+        background: #FBC2C4 !important;
+        color: #8a1f11 !important;
+      }
 </style>
 {% endblock %}
 
@@ -221,7 +225,7 @@ question_type = "{{ question.type }}"
 
                      {% if question.type == "integer" %}
                      Enter Integer:<br/>
-                     <input autofocus name="answer" type="number" id="integer" value={{ last_attempt|safe }} />
+                     <input autofocus name="answer" type="number" id="integer" value="{{ last_attempt|safe }}" />
                      <br/><br/>
                      {% endif %}
 
@@ -233,7 +237,7 @@ question_type = "{{ question.type }}"
 
                      {% if question.type == "float" %}
                      Enter Decimal Value :<br/>
-                     <input autofocus name="answer" type="number" step="any" id="float" value={{ last_attempt|safe }} />
+                     <input autofocus name="answer" type="number" step="any" id="float" value="{{ last_attempt|safe }}" />
                      <br/><br/>
                      {% endif %}