ok

firanka/series/range.py

@@ -25,8 +25,9 @@ class Range(object):
     def __init__(self, *args):
         if len(args) == 1:
             rs, = args
-            assert rs[0] in '<('
-            assert rs[-1] in '>)'
+
+            if (rs[0] not in '<(') or (rs[-1] not in '>)'):
+                raise ValueError('Must start with < or ( and end with ) or >')
 
             lend_inclusive = rs[0] == '<'
             rend_inclusive = rs[-1] == '>'

tests/test_series/test_range.py

@@ -14,6 +14,10 @@ class TestRange(unittest.TestCase):
     def test_str(self):
         self.assertEqual(str(Range(-1, 1, True, True)), '<-1;1>')
 
+    def test_constructor(self):
+        self.assertRaises(ValueError, lambda: Range('#2;3>'))
+        self.assertRaises(ValueError, lambda: Range('(2;3!'))
+
     def test_contains(self):
         self.assertFalse(-1 in Range('<-10;-1)'))
         self.assertTrue(-10 in Range('<-10;-1)'))