Merge pull request #10 from lambda-feedback/tr172-give-better-feedback-when-response-is-not-a-number

Added error message and feedback if answer or response is not a number

Author: KarlLundengaard

app/docs/user.md

@@ -1,3 +1,7 @@
 # IsSimilar 
 
-Use this evaluation function to check if the student's reponse is within a tolerance range defined in `params`. Works exactly like the [numpy.isclose](https://numpy.org/doc/stable/reference/generated/numpy.isclose.html#numpy.isclose) function. Valid params include `atol` and `rtol` (absolute and relative tolerances) which can be used in combination, or alone.
+Use this evaluation function to check if the student's reponse is within a tolerance range defined in `params`. Works exactly like the [numpy.isclose](https://numpy.org/doc/stable/reference/generated/numpy.isclose.html#numpy.isclose) function. Valid params include `atol` and `rtol` (absolute and relative tolerances) which can be used in combination, or alone.
+
+**Note:** If the answer is not a number, all responses will generate an error.
+
+**Note:** If the response is not a number, a feedback message asking the user to submit a number will be returned.

app/evaluation.py

@@ -27,13 +27,25 @@ def evaluation_function(response, answer, params) -> dict:
     is_correct = None
     real_diff = None
 
-    real_diff = abs(response - answer)
+    if not (isinstance(answer, int) or isinstance(answer, float)):
+        raise Exception("Answer must be a number.")
+
+    real_diff = None
     allowed_diff = atol + rtol * abs(answer)
     allowed_diff += spacing(answer)
-    is_correct = bool(real_diff <= allowed_diff)
+    is_correct = False
+    feedback = ""
+    if not (isinstance(response, int) or isinstance(response, float)):
+        feedback = "Please enter a number."
+    else:
+        real_diff = abs(response - answer)
+        allowed_diff = atol + rtol * abs(answer)
+        allowed_diff += spacing(answer)
+        is_correct = bool(real_diff <= allowed_diff)
 
     return {
         "is_correct": is_correct,
         "real_diff": real_diff,
         "allowed_diff": allowed_diff,
+        "feedback": feedback,
     }

app/evaluation_tests.py

@@ -212,5 +212,37 @@ def test_possible_bug_with_atol(self):
         self.assertEqual(result_under.get("is_correct"), False)
         self.assertEqual(result_over.get("is_correct"), False)
 
+    def test_answer_is_not_number(self):
+        body = {
+            "response": 2,
+            "answer": "two",
+            "params": {
+                "rtol": 0.2
+            },
+        }
+
+        self.assertRaises(
+            Exception,
+            evaluation_function,
+            body["response"],
+            body["answer"],
+            {},
+        )
+
+    def test_response_is_not_number(self):
+        body = {
+            "response": "two",
+            "answer": 2,
+            "params": {
+                "rtol": 0.2
+            },
+        }
+
+        response = evaluation_function(body['response'], body['answer'],
+                                       body.get('params', {}))
+
+        self.assertEqual(response.get("is_correct"), False)
+        self.assertEqual("Please enter a number." in response.get("feedback"), True)
+
 if __name__ == "__main__":
     unittest.main()