Enable code coverage

[oleksandr-kuzmenko]

I propose to add code coverage to this repo.
Can someone from members enable integration with codecov.io?

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@042cd5d). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #200   +/-   ##
=========================================
  Coverage          ?   92.85%           
=========================================
  Files             ?        3           
  Lines             ?      196           
  Branches          ?       59           
=========================================
  Hits              ?      182           
  Misses            ?        9           
  Partials          ?        5

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 042cd5d...1bc6235. Read the comment docs.

[oleksandr-kuzmenko]

codecov/project — No report found to compare against

I think it's OK for the first PR with codecov

[existentialism]

Couple things:

• Probably want to only include src, no sense in doing coverage on the data files, etc.

• Should set all: true to include any files that don't have any tests

• To get better coverage results, let's instrument the code via babel-plugin-instanbul (via BABEL_ENV/NODE_ENV).

[oleksandr-kuzmenko]

@existentialism done.
But it looks like babel-plugin-instanbul does not work with Node.js 0.10/0.12. Should we support the Node.js 0.10/0.12?

[existentialism]

@Alxpy for master we should use 3.1.2, and can bump to 4.0 on 2.0, if you don't mind making that change, I'll follow it up with some tweaks for CI/documentation

[existentialism]

@Alxpy made a few tweaks, please review!

[oleksandr-kuzmenko]

@existentialism LGTM!

[existentialism]

@Alxpy thanks again!