under-the-hood of test runner: spec reporter.js

function Spec(runner, options) {
  Base.call(this, runner, options);

  runner.on(Runner.constants.EVENT_RUN_BEGIN, function () {
    Base.consoleLog();
  });
   
  // more ....

  runner.on(Runner.constants.EVENT_TEST_PASS, function (test) {
    var fmt =
      indent() +
      color("checkmark", "  " + Base.symbols.ok) +
      color("pass", " %s") +
      color(test.speed, " (%dms)");
    Base.consoleLog(fmt, test.title, test.duration);
  });

  runner.on(Runner.constants.EVENT_TEST_FAIL, function (test) {
    Base.consoleLog(indent() + color("fail", "  %d) %s"), ++n, test.title);
  });

  runner.once(Runner.constants.EVENT_RUN_END, self.epilogue.bind(self));
}