New test on sub

tests/test_cturmit.py

@@ -124,7 +124,7 @@ class TurmitOperationTestCase(unittest.TestCase):
         ''' Test turmit sub() method '''
         self._rpn('sub')
 
-        t = Turmit()
+        t = Turmit(max_int=0xFFFF)
 
         t._push(50)
         t._push(8)
@@ -143,6 +143,12 @@ class TurmitOperationTestCase(unittest.TestCase):
         self.assertEqual(t._cur, 0)
         self.assertEqual(t.shead, 0)
 
+        t._push(8)
+        t._push(50)
+        t.sub()
+        self.assertEqual(t._cur, 1)
+        self.assertEqual(t.shead, 0xFFFF + (8 - 50))
+
     def test_mul(self):
         ''' Test turmit mul() method '''
         self._rpn('mul')