Add source map tests

[novemberborn]

Tests _rewritePath() as requested by @bcoe in #66.

I'd like to add a test for reading a source map file but I'm not quite sure where to put it. I mean I can test the add() method I suppose but there's no real test even verifying it's called. @bcoe any ideas? Happy with the coverage we have now?

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This bumps source-map-fixtures. I've added a sourceFile path which can be used to create the mappedPath from #76.

I realized the generated coverage report already applied source maps. It now writes the raw coverage file instead.

I've added a few more fixtures (with coverage) to test _rewritePath().

[bcoe]

@novemberborn one other annoying thing worth keeping in mind, I started doing a bunch of Windows testing on the weekend and, with the source-map fixtures, we run into issues with path.sep -- whether / or \ is used is all over the place:

• istanbul seems to sometimes set ./.
• we sometimes set ./.

Now, our core functionality does almost work on Windows without path.sep problems -- I hunted down the problem with spawning -- but the test suite is a ways of working; it might be smart to abstract the fixture lookup to not care about path.sep ... or something like that.

[novemberborn]

it might be smart to abstract the fixture lookup to not care about path.sep ... or something like that.

source-map-fixtures uses path.join() so I think it's just the test itself which prefixes with ./.

[bcoe]

@novemberborn the generated coverage file varies in path.sep usage too I think.

[bcoe]

If you ever get adventurous, this is what I use for Windows Node testing, it's free and works pretty well on OSX:

https://github.com/xdissent/ievms

[novemberborn]

@novemberborn the generated coverage file varies in path.sep usage too I think.

Ah yes it would. Maybe you could track progress in an issue and we can hash stuff out there? Can we use Travis to test Node on Windows?

[novemberborn]

This is passing CI now.

[bcoe]

@novemberborn AppVeyor seems to be the best available:

https://ci.appveyor.com/project/bcoe/yargs

Let's move Windows chatting to a separate ticket, there's enough problems with Windows right now that it shouldn't block this branch 👍

[bcoe]