Unit tests for `FilterablePlugin`

[estilles]

I think before I continue work on PR #12 we should consider adding unit tests for FilterablePlugin. If you agree, I will submit a separate PR for this.

[SamyPesse]

Yes, it's a good idea

[estilles]

Awesome! I will start working on this tomorrow. Will use Mongoose 4.x for the tests.

[estilles]

I also suggest we implement Istanbul so we can keep track of the coverage.

[estilles]

@SamyPesse, while unit testing FilterablePlugin I noticed the following:

• .search() returns an empty mongoose query, which makes it difficult to make timely assertions
• I assume you deferred building to query because of the async nature of `Filterable

  query`

• I noticed almost every the use of promises on a number of synchronous methods called by Query#parse (via Filterable#query)
• As far as I can tell, the only "real" async method called by Query#parse is Query#filterFields
• And ... again from what I can tell ... the only async process done by Query#filterFields is invoking user provided async middleware to resolve values.

I also noticed that:

• .search() does not accept a callback argument (as does mongoose' Model#find and others).
• you cannot chain multiple .search() (as you currently can with Model#find). Well technically you can, but the last .search() wins

These last few would be nice to have, but they're not a deal breaker for me.

Did I understand all of this correctly or did I miss something?

If my observations are correct, then the only reason for Query#parse to be async is the middleware to resolve values. Everything else appears to by synchronous in nature. If we could figure out a way to processes these middleware synchronously, we could easily make .search() behave more like its mongoose counterparts.

Just a thought.

In the meantime, I'll try to figure out a way to test FilterablePlugin without making any dramatic changes to the existing code base.

[estilles]

I may have found a solution to the situation I described in my comment above. It will significantly simplify .search() and will make it more testable. I will include it in my PR so we can review and discuss.

[estilles]

Unit tests for FiltarablePlugin requires a complete refactoring of lib/mongoose.js in my opinion. We should revisit this issue at a later time, when the code is refactored for testability.