V4 menu test

Sorry, I'm not used to writing unit tests. I fixed the code by observing the changes of menu(v3) with distinct arguments was passed. While I was doing so, I noticed that the menu(v3) didn't act as it should.

While `@Html.MvcSiteMap().Menu(0, false, true, 2)` return:
* Home
 * About
 * Contact
 * A
     * A1
     * A2
     * A3
 * B
     * B1
     * B2

Then this `@Html.MvcSiteMap().Menu(1, false, true, 2)` should return:
 * About
 * Contact
 * A
     * A1
     * A2
     * A3
 * B
     * B1
     * B2

But it return nothing instead.
I can make v4 menu act like v3 menu, but how do I know if the v3 menu is correct or not.