Merge pull request #82 from benfitzpatrick/subtract-greater-timepoint

Rationalise duration output when subtracting timepoints
metomi · Jan 9, 2018 · 4c0b4f4 · 4c0b4f4
2 parents c0ae6fa + da763a5
commit 4c0b4f4
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/isodatetime/data.py b/isodatetime/data.py
@@ -1324,6 +1324,8 @@ def __cmp__(self, other):
 
     def __sub__(self, other):
         if isinstance(other, TimePoint):
+            if other > self:
+                return -1 * (other - self)
             other = other.copy()
             other.set_time_zone(self.get_time_zone())
             my_year, my_day_of_year = self.get_ordinal_date()
@@ -1333,8 +1335,6 @@ def __sub__(self, other):
                 diff_day += get_days_in_year_range(other_year, my_year - 1)
             else:
                 diff_day -= get_days_in_year_range(my_year, other_year - 1)
-            if diff_day < 0:
-                return -1 * (other - self)
             my_hour, my_minute, my_second = self.get_hour_minute_second()
             other_hour, other_minute, other_second = (
                 other.get_hour_minute_second())

diff --git a/isodatetime/tests.py b/isodatetime/tests.py
@@ -633,6 +633,21 @@ def get_timepoint_subtract_tests():
              "hour_of_day": 5, "time_zone_hour": 0, "time_zone_minute": 0},
             "P29DT19H"
         ),
+        (
+            {"year": 1969, "month_of_year": 7, "day_of_month": 20,
+             "hour_of_day": 20, "time_zone_hour": 0, "time_zone_minute": 0},
+            {"year": 1969, "month_of_year": 7, "day_of_month": 20,
+             "hour_of_day": 19, "time_zone_hour": 0, "time_zone_minute": 0},
+            "PT1H"
+        ),
+
+        (
+            {"year": 1969, "month_of_year": 7, "day_of_month": 20,
+             "hour_of_day": 19, "time_zone_hour": 0, "time_zone_minute": 0},
+            {"year": 1969, "month_of_year": 7, "day_of_month": 20,
+             "hour_of_day": 20, "time_zone_hour": 0, "time_zone_minute": 0},
+            "-PT1H"
+        ),
         (
             {"year": 1991, "month_of_year": 5, "day_of_month": 4,
              "hour_of_day": 5, "time_zone_hour": 0, "time_zone_minute": 0},