Create osmChangeset object, inherit from osmEntity

test/index.html

@@ -81,6 +81,7 @@
 
     <script src='spec/modes/add_point.js'></script>
 
+    <script src='spec/osm/changeset.js'></script>
     <script src='spec/osm/entity.js'></script>
     <script src='spec/osm/intersection.js'></script>
     <script src='spec/osm/multipolygon.js'></script>

test/spec/osm/changeset.js

@@ -0,0 +1,29 @@
+describe('iD.osmChangeset', function () {
+    it('returns a changeset', function () {
+        expect(iD.osmChangeset()).to.be.an.instanceOf(iD.osmChangeset);
+        expect(iD.osmChangeset().type).to.equal('changeset');
+    });
+
+    it('defaults tags to an empty object', function () {
+        expect(iD.osmChangeset().tags).to.eql({});
+    });
+
+    it('sets tags as specified', function () {
+        expect(iD.osmChangeset({tags: {foo: 'bar'}}).tags).to.eql({foo: 'bar'});
+    });
+
+    describe('#asJXON', function () {
+        it('converts a node to jxon', function() {
+            var node = iD.osmChangeset({tags: {'comment': 'hello'}});
+            expect(node.asJXON()).to.eql({
+                osm: {
+                    changeset: {
+                        tag: [{ '@k': 'comment', '@v': 'hello' }],
+                        '@version': 0.6,
+                        '@generator': 'iD'
+                    }
+                }
+            });
+        });
+    });
+});