BUG: BDay for n>5 bug if starting not on offset #2680

Author: changhiskhan

pandas/tseries/offsets.py

@@ -329,6 +329,8 @@ def apply(self, other):
             if abs(n) > 5:
                 k = n // 5
                 result = result + timedelta(7 * k)
+                if n < 0 and result.weekday() > 4:
+                    n += 1
                 n -= 5 * k
 
             while n != 0:

pandas/tseries/tests/test_offsets.py

@@ -274,6 +274,16 @@ def test_apply_large_n(self):
         result = dt + BDay(100) - BDay(100)
         self.assertEqual(result, dt)
 
+        off = BDay() * 6
+        rs = datetime(2012, 1, 1) - off
+        xp = datetime(2011, 12, 23)
+        self.assertEqual(rs, xp)
+
+        st = datetime(2011, 12, 18)
+        rs = st + off
+        xp = datetime(2011, 12, 26)
+        self.assertEqual(rs, xp)
+
     def test_apply_corner(self):
         self.assertRaises(Exception, BDay().apply, BMonthEnd())