diff --git a/tests.py b/tests.py
index 1f69ff2..68c74d1 100644
--- a/tests.py
+++ b/tests.py
@@ -52,5 +52,9 @@ def test_element_in_list(self):
         self.assertTrue(element_in_list('purple', ['blue', 'purple', 'pink']))
         self.assertFalse(element_in_list('yellow', ['blue', 'purple', 'pink']))
 
+    def surface_of_triangle(grundseite, heohe):
+        self.assertTrue(100, surface_of_triangle(10,10))
+        self.assertFalse(1234,surface_of_triangle(4,5))
+
 if __name__ == '__main__':
     unittest.main()