[4.0.0] Response headers and cookies are no longer prematurely sent

[SidRoberts]

Refs: #12908

[sergeyklay]

Could you please explain a bit more - why?

[SidRoberts]

The Application class is effectively responsible for turning HTTP requests into HTTP responses. It shouldn't assume that the response will actually be sent - which is particularly true in testing.

Application requests should be handled like this:

$response = $application->handle($uri);

$response->send();

Not this:

echo $application->handle($uri)->getContent();

[sergeyklay]

Thank you