Allow users to pass files on the CLI

[Avaq]

Motivation

I'm in the process of migrating from one test runner to Oletus, and I want to do it gradually. In order to do so, I want Oletus to run on a subset of all the files I have in ./test. This PR adds a feature where users can supply their own list of test files to the Oletus CLI, like: oletus test/file1.mjs test/file2.mjs. If no files are specified, we fall back to crawling the ./test/ directory.

This feature is not only useful for my specific case though. It'll also help users who have their tests in other places, eg: oletus src/**/*.test.mjs, and users who have their tests in nested directories.

Changes

• The first commit is a pure refactor which moves the directory crawling logic outside of the test running logic.
• The second commit builds on this to make the directory crawling part optional in the CLI, adding the provided list of files as a second option.

[bearror]

I must say that I'm positively surprised that there's a need to migrate to Oletus.

The implementation looks solid. A couple of things to mention, though.

• Run npx standard --fix to ensure crawler.mjs is consistent from a style perspective. (Sorry for the undocumented linting.)
• example.mjs needs to be updated as well, since it relies on the fixtures. Something like the following should be fine.

const fixtures = crawl('./test/fixtures/')

fixtures
  .then(async fixtures => {
    await run(fixtures, concise)

    return fixtures
  })
  .then(fixtures => {
    run(fixtures, verbose)
  })

---

Great work once again! Happy to get this merged.

[Avaq]

I must say that I'm positively surprised that there's a need to migrate to Oletus.

I have yet to find another test runner that supports native modules:

• Support ES6 style tests without transpiler usage mochajs/mocha#3006
• Please consider adding native support for ES modules jestjs/jest#4842
• AVA with --experimental-modules avajs/ava#1810

That said, I also appreciate the simplicity and speed of Oletus.

A couple of things

Will do

[bearror]

Thanks for the contribution. I'll bump the minor version

[Avaq]

Great! :)