Add CheckTimeout function

[fortytw2]

Allows for a configurable timeout without changing the previously exposed API :)

closes #5

cc/ @lukechampine @bradleyfalzon

[lukechampine]

This looks good, but it's still not very pretty if you want to use a channel or something else to trigger the check. Now that we have CheckTimeout, it's at least possible to run the check immediately via CheckTimeout(t, 0) -- it's just ugly.

I'm not sure what the best solution is, but perhaps look into the context package? If you had a CheckContext function, then you could do:

ctx, _ := context.WithTimeout(5 * time.Second)
defer leaktest.CheckContext(ctx)()

But since it's a context, you'd have many other ways of triggering it as well.

[fortytw2]

Hmmmm, that's a really interesting idea - I'll give it a shot later today, thanks for the input! 😃

[fortytw2]

Replaced by #12