Protractor: Testing multiple user logins for conflicts during updating

Here's an interesting test case:

My application requires users to log in.
It's designed similar to gmail. If you're logged in in a tab, if you open another tab, you're redirected to the main page, rather than the login page.

Any ideas how I can test the following:

User 1 logs in and begins to edit a field, but does not click save.
User 2 logs in and edits the same field, clicks save.
User 1 then clicks save, and should receive a conflict message.

I thought about using mocks, but I don't think this will help me. The check for conflicts is done at the database level (when you grab the text, you also grab a version number. When you update, it checks for version number. If it's the same, it updates and increments the version. If the version numbers are not the same, it gives you an error).

Solution

This should help you: https://github.com/angular/protractor/blob/master/docs/browser-setup.md#using-multiple-browsers-in-the-same-test

and here's an example: https://github.com/angular/protractor/blob/master/spec/interaction/interaction_spec.js