Enhance .failing output with issue links

[novemberborn]

#673 introduced test.failing() to describe tests that should fail. When writing those tests it's good practice to link to an issue tracking their eventual resolution.

Rather than adding a .see() helper as originally proposed we're now looking to support hyperlinks in code comments that precede the test.failing() declaration. These should be extracted using a Babel helper and output in the verbose and mini reporters.

See discussion: avajs/eslint-plugin-ava#110 (comment)

[jamestalmage]

I will tackle the Babel transform. @cgcgbcbc is working on the logger output in #837.

[novemberborn]

Rather than extracting links, should we extract any immediately preceding comment?

[jamestalmage]

That could get verbose. Part of the idea is to make it clickable in iTerm. You can always click into the file and read comments directly

[novemberborn]

It'll still be clickable.

[jamestalmage]

My thought was to keep it succinct. For large projects, you may have a number of known issues that are long lived. I want provide just enough output to nag people into action, without flooding the console with stuff they will likely ignore.

[sindresorhus]

Yup, only the link.