i don't think the first scenario described here is possible, as the new PageMod will be `include`d only on the `firstURL`, so it can't attach to `secondURL` (where the tab is when `counter==2`), so `onAttach` can't run before (or even without) going back in history.

as for the second scenario, when the `counter==3`, adding an `assert.equal` there would change nothing, as test would already fail (as empty) on a call to `done` if the `assert.equal(persisted)` didn't already run..