under-the-hood of test runner: runSuite.js

Runner.prototype.runSuite = function (suite, fn) {
  this.emit(EVENT_SUITE_BEGIN, (this.suite = suite))

  function done(errSuite) {
    // 6. run all afterAll hooks
    self.hook(HOOK_TYPE_AFTER_ALL, () => {
      self.emit(EVENT_SUITE_END, suite);
      fn(errSuite);
    });
  }

  function next() {
    curr = suite.suites[i++]; // grab next suite
    // 5. no suites left, done
    if (!curr) done();
    // 4. call suite
    runSuite(curr, next);
  }

  // 1. run all beforeAll hooks
  hook(HOOK_TYPE_BEFORE_ALL, () => {
    // 2. run tests + callback once complete
    runTests(suite, next)
  }
}