From d16828e7469eabb43b500298b766e234fe8a459c Mon Sep 17 00:00:00 2001
From: Iskren Chernev <iskren.chernev@gmail.com>
Date: Mon, 29 Dec 2014 11:10:10 +0200
Subject: [PATCH] Add quarter diff support

---
 moment.js              |  6 ++++--
 test/moment/quarter.js | 15 +++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/moment.js b/moment.js
index 9057be4d83..19a4169296 100644
--- a/moment.js
+++ b/moment.js
@@ -2270,7 +2270,7 @@
 
             units = normalizeUnits(units);
 
-            if (units === 'year' || units === 'month') {
+            if (units === 'year' || units === 'month' || units === 'quarter') {
                 // 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
@@ -2283,7 +2283,9 @@
                 daysAdjust += ((this.utcOffset() - moment(this).startOf('month').utcOffset()) -
                         (that.utcOffset() - moment(that).startOf('month').utcOffset())) * 6e4;
                 output += daysAdjust / diff;
-                if (units === 'year') {
+                if (units === 'quarter') {
+                    output = output / 3;
+                } else if (units === 'year') {
                     output = output / 12;
                 }
             } else {
diff --git a/test/moment/quarter.js b/test/moment/quarter.js
index f8a2f41259..cea5f84732 100644
--- a/test/moment/quarter.js
+++ b/test/moment/quarter.js
@@ -119,6 +119,21 @@ exports.quarter = {
         test.done();
     },
 
+    'quarter diff' : function (test) {
+        test.equal(moment('2014-01-01').diff(moment('2014-04-01'), 'quarter'),
+                -1, 'diff -1 quarter');
+        test.equal(moment('2014-04-01').diff(moment('2014-01-01'), 'quarter'),
+                1, 'diff 1 quarter');
+        test.equal(moment('2014-05-01').diff(moment('2014-01-01'), 'quarter'),
+                1, 'diff 1 quarter');
+        test.ok(Math.abs((4 / 3) - moment('2014-05-01').diff(
+                        moment('2014-01-01'), 'quarter', true)) < 0.00001,
+                'diff 1 1/3 quarter');
+        test.equal(moment('2015-01-01').diff(moment('2014-01-01'), 'quarter'),
+                4, 'diff 4 quarters');
+        test.done();
+    },
+
     'quarter setter bubble to previous year' : function (test) {
         var m;
         test.expect(7);