Ignore DST for day, week, month and year diffs

diff --git a/moment.js b/moment.js
index fd67ba5644a4300754df4498b4e31b3a000dcfae..15b1b633d53eebcedb852a0bffd6b7572501338b 100644 (file)
--- a/moment.js
+++ b/moment.js
@@ -1228,19 +1228,27 @@
             units = normalizeUnits(units);
 
             if (units === 'year' || units === 'month') {
+                // average number of days in the months in the given dates
                 diff = (this.daysInMonth() + that.daysInMonth()) * 432e5; // 24 * 60 * 60 * 1000 / 2
+                // difference in months
                 output = ((this.year() - that.year()) * 12) + (this.month() - that.month());
-                output += ((this - moment(this).startOf('month')) - (that - moment(that).startOf('month'))) / diff;
+                // adjust by taking difference in days, average number of days
+                // and dst in the given months.
+                output += ((this - moment(this).startOf('month')) -
+                        (that - moment(that).startOf('month'))) / diff;
+                // same as above but with zones, to negate all dst
+                output -= ((this.zone() - moment(this).startOf('month').zone()) -
+                        (that.zone() - moment(that).startOf('month').zone())) * 6e4 / diff;
                 if (units === 'year') {
                     output = output / 12;
                 }
             } else {
-                diff = (this - that) - zoneDiff;
+                diff = (this - that);
                 output = units === 'second' ? diff / 1e3 : // 1000
                     units === 'minute' ? diff / 6e4 : // 1000 * 60
                     units === 'hour' ? diff / 36e5 : // 1000 * 60 * 60
-                    units === 'day' ? diff / 864e5 : // 1000 * 60 * 60 * 24
-                    units === 'week' ? diff / 6048e5 : // 1000 * 60 * 60 * 24 * 7
+                    units === 'day' ? (diff - zoneDiff) / 864e5 : // 1000 * 60 * 60 * 24, negate dst
+                    units === 'week' ? (diff - zoneDiff) / 6048e5 : // 1000 * 60 * 60 * 24 * 7, negate dst
                     diff;
             }
             return asFloat ? output : absRound(output);

diff --git a/test/moment/diff.js b/test/moment/diff.js
index 957624582f2f2b3dd40e9ed33ba5231e31bf00d9..c3f2f8c7278f0e0478250bdff8b9c7e6425bf0eb 100644 (file)
--- a/test/moment/diff.js
+++ b/test/moment/diff.js
@@ -91,10 +91,17 @@ exports.diff = {
     },
 
     "diff across DST" : function(test) {
-        test.expect(2);
+        test.expect(9);
 
         test.equal(moment([2012, 2, 24]).diff([2012, 2, 10], 'weeks', true), 2, "diff weeks across DST");
-        test.equal(moment([2012, 2, 24]).diff([2012, 2, 10], 'days', true), 14, "diff weeks across DST");
+        test.equal(moment([2012, 2, 24]).diff([2012, 2, 10], 'days', true), 14, "diff days across DST");
+        test.equal(moment([2012, 2, 11]).diff([2012, 2, 11, 12], 'hours', true), -11, "diff hours across DST");
+        test.equal(moment([2012, 2, 11]).diff([2012, 2, 11, 12], 'days', true), -0.5, "diff days across DST");
+        test.equal(moment([2012, 2, 11]).diff([2012, 2, 11, 12], 'months', true), -1/62, "diff months across DST (half day in 31 day month)");
+        test.equal(moment([2012, 2, 11]).diff([2012, 2, 11, 12], 'months', true), -1/62, "diff months across DST (half day in 31 day month)");
+        test.equal(moment([2013, 10, 2]).diff([2013, 10, 17], 'months', true), -0.5, 'diff months across DST (15 days in 30 day month)')
+        test.equal(moment([2013, 10, 2]).diff([2013, 10, 17], 'days', true), -15, 'diff days across DST')
+        test.equal(moment([2013, 10, 2]).diff([2013, 10, 17], 'hours', true), -15 * 24 - 1, 'diff hours across DST (15 days minus 1 hour DST)')
         test.done();
     },