Add a runtime test

Author: Smit-create

integration_tests/test_str_03.py

@@ -19,6 +19,11 @@ def test_issue_1124():
     assert a[-2] == a[4]
     assert a[-4] == "2"
 
+    # runtime tests
+    k: i32 = len(a); i: i32
+    for i in range(k):
+        assert a[-i-1] == a[k-i-1]
+
 
 test_new_line()
 test_int()