Add test.only()

[unlight]

I could not find test.only in api documentation. Similar to tape's test.only or mocha's it.only.
Is it exists?

[vadimdemedes]

test.only does not exist at the moment. We're having a long discussion on test modifiers at the moment - #9.

[lijunle]

+1 on this feature.

I am considering to migrate from mocha to AVA. However, keep easy test failure debug experience is one of my concerns - test.only is the key to do so.

[sindresorhus]

👍 We plan to add this. Help welcome as we have a lot of other things to deal with right now.

[vadimdemedes]

Closing via #204.