function next(err) {
    // if we bail after first err
    if (self.failures && suite._bail) return fn();

    // next test
    test = tests.shift();

    // all done
    if (!test) return fn();

    // grep
    var match = self._grep.test(test.fullTitle());
    if (self._invert) match = !match;
    if (!match) return next();

    // pending
    if (test.pending) {
      self.emit('pending', test);
      self.emit('test end', test);
      return next();
    }

    // execute test and hook(s)
    self.emit('test', self.test = test);
    self.hookDown('beforeEach', function(){
      self.currentRunnable = self.test;
      self.runTest(function(err){
        test = self.test;

        if (err) {
          self.fail(test, err);
          self.emit('test end', test);
          return self.hookUp('afterEach', next);
        }

        test.state = 'passed';
        self.emit('pass', test);
        self.emit('test end', test);
        self.hookUp('afterEach', next);
      });
    });
  }
Run tests in the given `suite` and invoke
the callback `fn()` when complete.

@param {Suite} suite
@param {Function} fn
@api private