added test for approximating pi with a negative precision number and added functionality to return negaive one in this case to indicate error

src/main/py/trigonometry.py

@@ -2,6 +2,8 @@ import math
 from src.main.py.logarithmic_and_expo_and_root_calculations import potentiate
 
 def pi_approx_leibniz(precision):
+    if precision < 0:
+        return -1
     result = 0
     for i in range(precision):
         num = potentiate(-1, i)

src/test/py/test_trigonometry.py

@@ -15,6 +15,9 @@ class MyTestCase(unittest.TestCase):
             delta *= -1
         self.assertLess(delta, 0.01)
 
+    def test_pi_precision_negative_10_should_be_negative_1_for_error(self):
+        self.assertEqual(pi_approx_leibniz(-10), -1)
+
     def test_rad_2_to_deg_should_be_114_point_59(self):
         delta = rad2deg(2) - 114.59
         if delta < 0: