figure out how to test the deploy command

[mykmelez]

We need to figure out how to test the deploy command.

We can create a local Git repository and bootstrap an app in it to deploy, but then there's the question of how to test that deployment pushes it to its origin remote, which is normally on GitHub.

But deploy doesn't actually depend on GitHub itself, only on there being an origin "remote", which could presumably be another local repository. So it should be possible to test deploy without a dependency on a GitHub server.

We would just need to create two local repositories, one of which has the other as its origin; build the app in the first repository; and then test that the deploy command pushes the build output to the gh-pages branch in the origin repository.

[marco-c]

Looks interesting, I'll take a stab at it.

[mykmelez]

Marco, these tests broke the next time I merged a change to master (https://travis-ci.org/mozilla/oghliner/builds/85199186), because the tmp dir was apparently preserved across builds:

2. Deploy should update the gh-pages branch in the origin repo and publish files to it:
   Error: EEXIST, file already exists 'tmp'
   at Error (native)
   at Object.fs.mkdirSync (fs.js:747:18)
   at Context. (test/testDeploy.js:49:8)

[brendandahl]

The temp folder/file creation library I used in https://github.com/mozilla/oghliner/pull/63/files#diff-c792d04edfea01487109cfd6450c9ef8R4 worked pretty well.

[marco-c]

@mykmelez I think it was a timeout, which then caused the "tmp" directory to be preserved and thus the second test to fail.
It's likely that the test could actually need more time, as in this successful build (https://travis-ci.org/mozilla/oghliner/builds/85199186, which is yours retriggered) the test took 673ms (which is relatively close to the current timeout of 2 seconds).

Let's file a new issue if it happens again.
I'll also submit a PR to avoid failing following tests when the first runs out of time.