tl;dr
````` ruby
class Process::Status
  alias exited? success?

  def stopped?
    raise NotImplementedError
  end
end
`````

Here goes!  In MRI, the `#exited?` method is described as being `true` if the process exited normally, but doesn't explicitly say that the only exit code considered normal is `0`.  MRI also stipulates that `#exitstatus` is only available if the process has exited, which is *every time* in the case of Topaz and JRuby (haven't yet looked at Rubinius).

JRuby implements `#exited?` as a comparison with `0`, but (strangely?) the `#success?` method is implemented fairly differently despite still being a comparison with `0`.  I'm thinking now that I'd like to define `#exited?` as an alias for `#success?`.

As for `#stopped?`, MRI claims it is only `true` if the corresponding `wait` call had the `WUNTRACED` flag set, whereas JRuby raises `NotImplementedError`.  Perhaps I should follow JRuby's example here as well, but this kinda stinks given RubySpec's multi-assertion spec (sad face).  I suppose in this case I could just add some tests in the Topaz py.test suite.