Make nested-svg test more strict

Author: mdtusz

test/jasmine/tests/snapshot_test.js

@@ -150,7 +150,8 @@ describe('Plotly.Snapshot', function() {
     });
 
     describe('toSVG', function() {
-        var gd;
+        var parser = new DOMParser(),
+            gd;
 
         beforeEach(function() {
             gd = createGraphDiv();
@@ -163,19 +164,21 @@ describe('Plotly.Snapshot', function() {
             Plotly.plot(gd, subplotMock.data, subplotMock.layout).then(function() {
                 return Plotly.Snapshot.toSVG(gd);
             }).then(function(svg) {
-                var splitSVG = svg.split('<svg');
+                var svgDOM = parser.parseFromString(svg, 'image/svg+xml'),
+                    svgElements = svgDOM.getElementsByTagName('svg');
 
-                expect(splitSVG.length).toBe(2);
+                expect(svgElements.length).toBe(1);
             }).then(done);
         });
 
         it('should not return any nested svg tags of annotations', function(done) {
             Plotly.plot(gd, annotationMock.data, annotationMock.layout).then(function() {
                 return Plotly.Snapshot.toSVG(gd);
             }).then(function(svg) {
-                var splitSVG = svg.split('<svg');
+                var svgDOM = parser.parseFromString(svg, 'image/svg+xml'),
+                    svgElements = svgDOM.getElementsByTagName('svg');
 
-                expect(splitSVG.length).toBe(2);
+                expect(svgElements.length).toBe(1);
             }).then(done);
         });
     });