Handle ExportNamedDeclarations

[Victorystick]

Istanbul currently doesn't handle export var ..., and throws:

/Users/oskar/github/istanbul/lib/instrumenter.js:252
                        throw new Error('Internal error: attempt to prepend statements in disallowed (non-array) context');
                        ^

Error: Internal error: attempt to prepend statements in disallowed (non-array) context
    at Object.defaultWalker (/Users/oskar/github/istanbul/lib/instrumenter.js:252:31)
    at Object.Walker.apply (/Users/oskar/github/istanbul/lib/instrumenter.js:297:26)
    at Object.defaultWalker (/Users/oskar/github/istanbul/lib/instrumenter.js:237:47)
    at Object.Walker.apply (/Users/oskar/github/istanbul/lib/instrumenter.js:297:26)
    at Object.Walker.startWalk (/Users/oskar/github/istanbul/lib/instrumenter.js:281:18)
    at Object.Instrumenter.instrumentASTSync (/Users/oskar/github/istanbul/lib/instrumenter.js:554:25)
    at Object.Instrumenter.instrumentSync (/Users/oskar/github/istanbul/lib/instrumenter.js:468:25)
    at Object.<anonymous> (/Users/oskar/github/istanbul/exec.js:7:27)
    at Module._compile (module.js:425:26)
    at Object.Module._extensions..js (module.js:432:10)

This PR attempts to rectify this.

[gotwarlost]

You change does not pass the jshint check and does not have a unit test. Please fix / add.

[Victorystick]

How about this?

[gotwarlost]

Sorry man, I'm totally slammed this week - will get to it in 4-6 days.

[Victorystick]

No worries. I'll get out of your hair. 😉

[ftripier]

+1

[guybedford]

Instead of making the environment detection "pass", could you rather not just remove the conditional check in test-es6-export.js that tries to do environment detection?

[coveralls]

Coverage increased (+0.01%) to 97.566% when pulling d828255 on Victorystick:es-modules-support into ad8ab1d on gotwarlost:master.

[coveralls]

Coverage increased (+0.01%) to 97.566% when pulling d828255 on Victorystick:es-modules-support into ad8ab1d on gotwarlost:master.

[Victorystick]

Sorry for the delay. I've addressed all the issues. Let's get these changes in! 😄

[marvinhagemeister]

I just ran into this exact problem and found this PR. Skimming over the requested changes it looks good to me. Hope this will be merged soon, because this prevents code coverage for es6 environments.

[TrySound]

@gotwarlost Hi. When we can wait a release?

[goesbysteve]

Should this enable this to be instrument-able now?

export default {
  ...
}

I manually upgrade the dependency in https://github.com/deepsweet/babel-istanbul-loader to use babel-istanbul@0.11.x but I'm still getting unexpected token hitting an export default where an exports = works.