Rather than maintain our own test runner we should instead lean on the community and use Mocha which is very popular and also our test runner of choice in DevTools too.
Note that this commit doesn't remove the TestRunner source as it's still used for other unit tests, but they will be updated in a future PR and then we can remove the TestRunner.
The main bulk of this PR is updating the tests as the old TestRunner passed in contextual data via the `it` function callback whereas Mocha does not, so we introduce some helpers for the tests to make it easier.
This patch aligns Puppeteer testing infrastructure with the approach
we use in Puppeteer-Firefox.
This patch:
- makes all tests accept Puppeteer object as a function argument
rather than require it statically. This way we can pass either
Puppeteer or Puppeteer-Firefox to drive tests.
- renames the `puppeteer.spec.js` into `launcher.spec.js`. The
`puppeteer.spec.js` is now the entry point for all cross-browsers
tests.
Tracing is working on a per-browser level, not per-page. In order
to paralellize these tests effectively and properly, each should run
a designated browser.
Today, we have tests split into multiple files, with files pulling
tests from some other files.
This patch starts explicitly gathering all tests from the same
`test.js` file.
Drive-By: move one test from `browser.spec.js` into `puppeteer.spec.js`
since it starts browser itself.
