cant do end before start

2 files changed, 2 insertions, 0 deletions

diff --git a/date.py b/date.py
index b44c8b0..375e220 100644
--- a/date.py
+++ b/date.py
@@ -84,6 +84,7 @@ else:
         return end
 
     def nb_open_days(start, end):
+        assert start <= end
         days = int(math.ceil((end - start).days))
         weeks, plus = divmod(days, 7)
         if start.day_of_week > end.day_of_week:
diff --git a/test/unittest_date.py b/test/unittest_date.py
index 3785e63..2a30de6 100644
--- a/test/unittest_date.py
+++ b/test/unittest_date.py
@@ -65,6 +65,7 @@ class DateTC(TestCase):
         x = now()
         self.assertEquals(nb(x,x), 0)
         self.assertEquals(nb(x,x+0.5), 1)
+        self.assertRaises(AssertionError, nb, x, x-1)
     
 if __name__ == '__main__':
     unittest_main()