over 1000 and minus

String calculator

@@ -112,6 +112,10 @@ class TestStingCalculator(unittest.TestCase):
         self.assertEqual(self.calculator.add("1,1001,2,3"),6)
     def test_add_numbers_greater_than_1000_1002(self):
         self.assertEqual(self.calculator.add("1002,1,2,3"),6)
+    def test_add_numbers_greater_1000_and_minus(self):
+        with self.assertRaises(ValueError) as e:
+            self.calculator.add("//;\n-3,4;1001")
+        self.assertEqual(str(e.exception),"negatives not allowed: -3")