Remove duplicate 'firstresult' test

[goodboy]

Remove test_method_ordering.test_decorator_functional as it is
duplicate of an already incomplete test.

Fix up test_firstresult_definition to be more more complete and actually test
that when multiple hooks are registered for a spec marked with firstresult
the first result is only ever returned.

Fixes #61

[goodboy]

woa weird.. Is my assertion wrong there?
I thought the first result should come from the first registered plugin?

Ope, no, it comes from the last registered.

Fixing...

[RonnyPfannschmidt]

now thats a really interesting issue - this shouldn't happen - i was under the impression we would at least use registration order

man seriously - every time i think there cant be a worse horror pytests legacy has one jsut ever more so "interesting" one

[nicoddemus]

I think the logic is that core hooks are registered first, user hooks are registered last. So they are called in reverse order so user hooks can override core hooks.

But I agree it is slightly confusing.

[RonnyPfannschmidt]

thanks for fixing the test - given the comments/properties i wonder if there is a more nice way to express the behaviour

[goodboy]

@RonnyPfannschmidt the label firstresult you mean? Yeah I think it could be communicated a little more clearly for sure; not sure what better name would be though.

It's funny cause if you think about registration order it's more like lastresult lolz.

[nicoddemus]

The label firstresult is fine IMHO, what is perhaps not clear is the order in which plugins are called. Perhaps we should add a "plugin call order" section to the docs?

[goodboy]

@nicoddemus yeah good call. Do you mind making an issue?

[nicoddemus]

Definitely, done: #64