From d83ec7f1eb4862b58b62022da76d9d809c3996ac Mon Sep 17 00:00:00 2001
From: Brandon Liu <bdon@bdon.org>
Date: Sat, 19 Jan 2013 22:29:11 -0800
Subject: [PATCH] Create method history.hasChanges

---
 js/id/graph/history.js     |  6 ++++++
 test/spec/graph/history.js | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/js/id/graph/history.js b/js/id/graph/history.js
index e31fa5ef9..bf7cdfc88 100644
--- a/js/id/graph/history.js
+++ b/js/id/graph/history.js
@@ -109,6 +109,12 @@ iD.History = function() {
             };
         },
 
+        hasChanges: function() {
+            return !!d3.sum(d3.values(this.changes()).map(function(c) {
+                return c.length;
+            }));;
+        },
+
         imagery_used: function(source) {
             if (source) imagery_used = source;
             else return _.without(
diff --git a/test/spec/graph/history.js b/test/spec/graph/history.js
index 15fe10964..c3fa536f1 100644
--- a/test/spec/graph/history.js
+++ b/test/spec/graph/history.js
@@ -126,6 +126,18 @@ describe("iD.History", function () {
         });
     });
 
+    describe("#hasChanges", function() {
+        it("is true when any of change's values are nonempty", function() {
+            var node = iD.Node();
+            history.perform(function (graph) { return graph.replace(node); });
+            expect(history.hasChanges()).to.eql(true);
+        });
+
+        it("is false when any of change's values are empty", function() {
+            expect(history.hasChanges()).to.eql(false);
+        });
+    });
+
     describe("#reset", function () {
         it("clears the version stack", function () {
             history.perform(action, "annotation");