add another test for checkout

src/diagrams/gitGraph/gitGraphParser.spec.js

@@ -33,6 +33,7 @@ describe('when parsing a gitGraph',function() {
         expect(parser.yy.getDirection()).toBe("TB");
         expect(Object.keys(parser.yy.getBranches()).length).toBe(1);
     });
+
     it('should checkout a branch', function () {
         var str = 'gitGraph:\n' +
         'branch new\n' +
@@ -45,6 +46,22 @@ describe('when parsing a gitGraph',function() {
         expect(parser.yy.getCurrentBranch()).toBe("new");
     });
 
+    it('should add commits to checked out branch', function () {
+        var str = 'gitGraph:\n' +
+        'branch new\n' +
+        'checkout new\n' +
+        'commit\n'+
+        'commit\n'
+
+        parser.parse(str);
+        var commits = parser.yy.getCommits();
+
+        expect(Object.keys(commits).length).toBe(2);
+        expect(parser.yy.getCurrentBranch()).toBe("new");
+        var branchCommit = parser.yy.getBranches()['new'];
+        expect(branchCommit).not.toBeNull();
+        expect(commits[branchCommit].parent).not.toBeNull();
+    });
     it('should handle commit with args', function () {
         var str = 'gitGraph:\n' +
         'commit "a commit"\n';