Fix test that was never running in test_mutations.py

Author: jhgg

tests/core_execution/test_mutations.py

@@ -94,7 +94,7 @@ def test_evaluates_mutations_serially():
         }
 
 
-def evaluates_mutations_correctly_in_the_presense_of_a_failed_mutation():
+def test_evaluates_mutations_correctly_in_the_presense_of_a_failed_mutation():
     doc = '''mutation M {
       first: immediatelyChangeTheNumber(newNumber: 1) {
         theNumber
@@ -128,5 +128,5 @@ def evaluates_mutations_correctly_in_the_presense_of_a_failed_mutation():
         }
     assert len(result.errors) == 2
     # TODO: check error location
-    assert result.errors[0].undefined_field_message == 'Cannot change the number'
-    assert result.errors[1].undefined_field_message == 'Cannot change the number'
+    assert result.errors[0]['message'] == 'Cannot change the number'
+    assert result.errors[1]['message'] == 'Cannot change the number'