added test to use sqrt_power with float as exponent

src/test/py/test_calculations_with_roots.py

@@ -24,6 +24,9 @@ class calculationsWithRoots(unittest.TestCase):
     def test_sqrt_negative_4_to_power_of_3_should_be_negative_one_for_error(self):
         self.assertEqual(sqrt_power(-4, 3), -1)
 
+    def test_sqrt_16_to_power_of_point5_should_be_2(self):
+        self.assertEqual(sqrt_power(16, 0.5), 2)
+
 
 if __name__ == '__main__':
     unittest.main()