added test to check if multiplication of two roots with both negative numbers returns minus1 to indicate error as well as corresponding functionality

src/main/py/calculations_with_roots.py

@@ -1,4 +1,6 @@
 import math
 
 def multiplyRoots(first_number, second_number):
+    if first_number < 0 or second_number < 0:
+        return -1
     return math.sqrt(first_number * second_number)

src/test/py/test_calculations_with_roots.py

@@ -15,6 +15,9 @@ class calculationsWithRoots(unittest.TestCase):
     def test_sqrt_2_times_sqrt_8_should_be_4(self):
         self.assertEqual(multiplyRoots(2, 8), 4)
 
+    def test_sqrt_negative_2_times_sqrt_negative_8_should_be_negative_one_for_error(self):
+        self.assertEqual(multiplyRoots(-2, -8), -1)
+
 
 if __name__ == '__main__':
     unittest.main()