Merge pull request #2353 from edx/alex/no_error_on_empty_answer_to_master

Alex/no error on empty answer to master

common/lib/capa/capa/responsetypes.py

@@ -949,8 +949,6 @@ class NumericalResponse(LoncapaResponse):
         if self.range_tolerance:
             if isinstance(student_float, complex):
                 raise StudentInputError(_(u"You may not use complex numbers in range tolerance problems"))
-            if isnan(student_float):
-                raise general_exception
             boundaries = []
             for inclusion, answer in zip(self.inclusion, self.answer_range):
                 boundary = self.get_staff_ans(answer)

common/lib/capa/capa/tests/test_responsetypes.py

@@ -649,7 +649,7 @@ class StringResponseTest(ResponseTest):
     def test_case_sensitive(self):
         # Test single answer
         problem_specified = self.build_problem(answer="Second", case_sensitive=True)
-        
+
         # should also be case_sensitive if case sensitivity is not specified
         problem_not_specified = self.build_problem(answer="Second")
         problems = [problem_specified, problem_not_specified]
@@ -1105,11 +1105,13 @@ class NumericalResponseTest(ResponseTest):
         with self.assertRaises(StudentInputError):
             problem.grade_answers(input_dict)
 
-        # test isnan variable
+        # test isnan student input: no exception,
+        # but problem should be graded as incorrect
         problem = self.build_problem(answer='(1, 5)')
         input_dict = {'1_2_1': ''}
-        with self.assertRaises(StudentInputError):
-            problem.grade_answers(input_dict)
+        correct_map = problem.grade_answers(input_dict)
+        correctness = correct_map.get_correctness('1_2_1')
+        self.assertEqual(correctness, 'incorrect')
 
         # test invalid range tolerance answer
         with self.assertRaises(StudentInputError):