Estree compatibility as plugin

[danez]

Q	A
Bug fix?	no
Breaking change?	no
New feature?	yes
Deprecations?	no
Spec compliancy?	yes
Tests added/pass?	yes
Fixed tickets	Fixes #278
License	MIT

New plugin to enable estree compatible output.

A new test runner was added, which runs all tests which are throwing tests with the estree plugin. All tests that should throw in non-estree should still throw in estree mode.

• Add compare test between babylon-estree and other parser (flow and/or espree)
• Extend ExpressionStatement to indicate a directive prologue estree/estree#6

[codecov-io]

Codecov Report

Merging #277 into master will increase coverage by 0.05%.
The diff coverage is 99.27%.

@@            Coverage Diff            @@
##           master    #277      +/-   ##
=========================================
+ Coverage   97.74%   97.8%   +0.05%     
=========================================
  Files          20      21       +1     
  Lines        3367    3504     +137     
  Branches      888     925      +37     
=========================================
+ Hits         3291    3427     +136     
  Misses         29      29              
- Partials       47      48       +1

Impacted Files	Coverage Δ
src/parser/index.js	97.95% <100%> (+0.13%)	✅
src/parser/expression.js	97.33% <100%> (ø)	✅
src/index.js	100% <100%> (ø)	✅
src/plugins/estree.js	99.24% <99.24%> (ø)

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[fkling]

This is great, thank you @danez! Any idea when this could be released? I'm happy to help getting this out sooner rather than later.

[danez]

I'm currently working on getting ObjectMethod/ObjectProperty back to Property.
That should be already everything that is left, as far as I can see right now.
So I don't want to give any estimates that I can't keep, but I think it should be ready next week.

[fkling]

That is great, thank you. I will wait then 😃

[DrewML]

This is such a big deal!

[danez]

Quick update, it already works as expected (with some minor things missing, see top) but I'm still working on doing cross-testing with flow and espree, which already revealed some issues.

[danez]

I did not commit the comparison tests between babylon with estree and espree/flow in this branch as there are a lot of mismatches. Most of them are that espree/flow cannot parse the fixture (and yes all experimental stuff excluded). I need to go through this at some point and fix on our end or report to the other parsers.

The tests are in a separate branch estree-test