Rewrite unit tests to not change the process's CWD, replace Traceur with 6to5, replace Grunt with gulp

[UltCombo]

Closes #86 Closes #87 Paving the way for #96 (allow APIs to receive a sitePath argument)

@jaydson this PR is not ready for merging yet, but feel free to take a look if you have time.

I've coded this while half asleep, so I'll perform a self-review tomorrow if I have time as well.

The main benefit of the Grunt -> gulp switch here is that gulp is imperative, providing lower-level control. I've prepared the gulpfile's watch task taking in consideration projects which take a long time to build/test (improving the test time is in my TODO list, but given Harmonic's nature, odds are the tests will still take a considerable amount of time even after being properly refactored).

More specifically, the watch task works in "batch" mode -- that is, if you edit/create/remove one or more files while a build/test is running, it will wait until the test is finished and then process all the files that changed while the test was running, thus generating an incremental build and running tests again.

If anyone has trouble reading the gulpfile, take a look at the (simplified) stream flow diagram.

TODO:

• [x] build task's copySrc is not copying files which have been negated by globs before being re-included
• [x] check why build task takes so long to finish when passing an absolute sitePath argument and CWD != sitePath (the harmonic build in the unit test takes about 11 seconds to finish in Windows) -- @jaydson mind checking how long it takes for npm test to conclude in your computer?

[UltCombo]

Even in Travis, harmonic build used to take about ~1.8s and now it took 5~6s. Thing is, it requires a rather specific scenario to trigger this slow down (as detailed in the OP), so end users shouldn't be hit by it. I'll investigate it after fixing the other more serious issues in this PR.

[UltCombo]

Passing the path around all functions is repetitive, but that is necessary to avoid global state.

In the future, we can switch Harmonic from a singleton to a constructor/factory pattern and pass the path when instantiating it in order to avoid this cruft.

[UltCombo]

The gulp build task's copy pipe should be working fine now.

There's still the harmonic build taking a long time to run in the unit tests. Weirdly enough, it looks like its run time has increased after I installed a few more dependencies -- which is rather odd, seeing as harmonic build shouldn't touch the node_modules directory. I'll investigate this issue as soon as possible.

[UltCombo]

Can someone please review this PR? By review I mean two things:

• Check whether it is working properly: try out to this branch, install the dependencies (delete the node_modules directory then run npm install), npm link and check if it can still build sites fine.
• Opinions/suggestions: I've added a sitePath parameter to pretty much all parser/helper/util functions so it is much easier to test the API now. All CLI commands also take the site path as an optional last parameter now. Opinions/suggestions on how we can improve this would be great.

//cc @jaydson @leobalter

[jaydson]

Trying out here. The build time It's really odd: ✓ should build the Harmonic site (5152ms) ✓ should create and build a new post (5106ms)

[jaydson]

But it seems to be working fine.

[UltCombo]

Yep, I noticed it too (see this comment). I did some preliminary testing a couple days ago and the build time for the usual cases (e.g. running harmonic build) is the same as before, the slow down problem only seemed to appear when passing the new path parameter (e.g. harmonic build "/absolute/path/to/project") and the given path is not the current working directory. It is a rather weird issue, I'll investigate a bit more before merging.

Thanks @jaydson for testing. :D

[UltCombo]

Found the issue!

Harmonic was instantiating nunjucks.FileSystemLoader which by default watches the template directory for changes. The watcher prevented the process from exiting. Weirdly enough, passing true to the noWatch parameter did not stop nunjucks from watching the template files (possible bug? Need more testing before submitting an issue in their repo).

It is also odd how we haven't been hit by this issue before.

Anyway, I've instantiated the nunjucks.Environment using the Nunjucks simple API's nunjucks.configure passing the { watch: false } option (see https://github.com/es6rocks/harmonic/commit/331100400f586dcad1a419ef566a5b22fa9a8849), now build times are back to normal! :fireworks:

[UltCombo]

Alas, "back to normal" is not accurate, seeing as harmonic build was never affected. The build time was only slow when providing the new optional path argument: harmonic build /absolute/path/to/project.

[jaydson]

Awesome job @UltCombo !!!