In an ideal world (where everything is free and easy to implement) we'd want both unit tests and browser tests.

Of course we don't live in an ideal world so that may not be the right approach for blimp::Engine::Tab :)  For whoever picks up this bug, if we decide not to write a unit test for Tab, I'd be interested in understanding why (insufficient test tools, unit testing this class isn't particularly useful, too difficult, had dependencies on stuff that's hard to test, etc.).

It looks like all the dependencies are injected, so it looks like a unit-test is feasible. There is no existing MockWebContents and the API surface is huge, but we could at least re-use it to test the PageLoadTracker. However, PageLoadTracker is should also be tested against a real WebContents, so we can trap any changes in the semantics there.

So basically I think both browser & unit-tests would be advisable.

Obsolete, WontFix.