refactor: update lib/reporter/multi.js to ES6

[lusarz]

No description provided.

[devoto13]

Looks good!

[johnjbarton]

Do we know what this code does? what happens if we add or remove an "adapter" from a reporter?

[lusarz]

MultiReporter instance is returned from createReporters method:

karma/lib/reporter.js

Line 155 in ac4e1a9

return new MultiReporter(reporters)

so MultiReporter seems to be container that group a few reporters.

According to this implementation:

karma/lib/reporters/base.js

Lines 48 to 59 in 35965d9

	this.write = function () {
	var msg = util.format.apply(null, Array.prototype.slice.call(arguments))
	var self = this
	this.adapters.forEach(function (adapter) {
	if (!helper.isDefined(adapter.colors)) {
	adapter.colors = useColors
	}
	if (!helper.isDefined(self.EXCLUSIVELY_USE_COLORS) || adapter.colors === self.EXCLUSIVELY_USE_COLORS) {
	return adapter(msg)
	}
	})
	}

adapter is function invoked with message inside reporter.write method. I guess adapter may allow to print to stdout, print to file etc.

[devoto13]

@lusarz is right. adapters allow to configure where to send reporters' output (one or multiple destinations). It is used in one place - lib/middleware/runner.js. It basically adds response output stream as an adapter to all reporters (to send reporters output to the karma run script) and removes it after test run is complete.

[johnjbarton]

Thanks! The change is simple enough but we don't have any tests and I did not see the code that uses this.