underscore -> lodash

[rosston]

Fixes #88.

Changes:

• _.template: minor API change
• _.contains: called includes in lodash 4
• _.keys: underscore simply used Object.keys if available, so cut out the middleman

Why lodash instead of underscore?

• lodash is more popular (see npm stats)
• lodash follows semantic versioning
• lodash has more functions (e.g., _.get which could come in handy for #62 and #66)

[rosston]

Other underscore/lodash functions used in index.js but left unchanged:

• _.extend: aliased to _.assignIn in lodash, seems to match underscore version, specifically that it extends from inherited properties as well
• _.union: seems to match underscore version
• _.difference: seems to match underscore version, although this one is a little harder to inspect due to the complexity of the lodash version
• _.isFunction: seems to match underscore version

All comparisons made by checking the docs and source for lodash 4.6.1 and underscore 1.5.2.

[floatingLomas]

I don't really have any cycles to review this right now, but I wanted to say:

:+1: :+1: :+1: :+1: :+1: :+1: :+1:

[rosston]

No worries! I got caught up in other things, so haven't done the last bit of testing before merging. I plan to do another check to make sure lodash is API-compatible with underscore for the functions we're using.

[rosston]

Alright, I finally did the last bit of testing I wanted to do. I cloned the underscore repo, checked out the 1.5.2 tag, and threw lodash in the test suite. Here's the git diff:

And here are the results for each of the underscore functions we previously used in index.js and test/test.js:

• _.keys (ignored, since I replaced it with Object.keys in our code)
• _.contains ✅
• _.difference ✅
• _.extend ✅
• _.isFunction ✅
• _.template ✅
• _.union ❌

The only failed test for _.union is this:

result = _.union(null, [1, 2, 3]);
deepEqual(result, [null, 1, 2, 3]);

...which seems like a pretty worthless piece of functionality. I also manually tested undefined, and as (sort of) expected: underscore 1.5.2 keeps undefined in the resulting array, lodash 4.11.1 drops the undefined entirely. With where we use _.union (see https://github.com/bithavoc/express-winston/blob/99b3e2d/index.js#L252-253), this difference will have no practical effect, since options.bodyWhitelist and options.bodyBlacklist fall back to the base exported versions.

So! In summary, everything is fine, and I'm merging this. 😄