Merge pull request #163 from spencerkclark/fix-dayofyr

Fix dayofyr after timedelta addition issue

cftime/_cftime.pyx

@@ -1802,7 +1802,7 @@ cdef tuple add_timedelta(datetime dt, delta, bint (*is_leap)(int), bint julian_g
             day += delta_days
             delta_days = 0
 
-    return (year, month, day, hour, minute, second, microsecond, -1, 1)
+    return (year, month, day, hour, minute, second, microsecond, -1, -1)
 
 # Add a datetime.timedelta to a cftime.datetime instance with the 360_day calendar.
 #
@@ -1844,7 +1844,7 @@ cdef tuple add_timedelta_360_day(datetime dt, delta):
     year += (month - 1) // 12
     month = (month - 1) % 12 + 1
 
-    return (year, month, day, hour, minute, second, microsecond, -1, 1)
+    return (year, month, day, hour, minute, second, microsecond, -1, -1)
 
 # Calendar calculations base on calcals.c by David W. Pierce
 # http://meteora.ucsd.edu/~pierce/calcalcs

test/test_cftime.py

@@ -1533,5 +1533,13 @@ def test_replace_dayofyr_or_dayofwk_error(date_type, argument):
     with pytest.raises(ValueError):
         date_type(1, 1, 1).replace(**{argument: 3})
 
+
+def test_dayofyr_after_timedelta_addition(date_type):
+    initial_date = date_type(1, 1, 2)
+    date_after_timedelta_addition = initial_date + timedelta(days=1)
+    assert initial_date.dayofyr == 2
+    assert date_after_timedelta_addition.dayofyr == 3
+
+
 if __name__ == '__main__':
     unittest.main()