Add a possibility to reset CaptureOutput

[SchulteMarkus]

Hi there,

I am using OutputCapture as part of my integration tests.
I am testing the spring-boot application as suggested in boot-features-testing-spring-boot-applications.
After my application is booted in my integration-test, I am using HtmlUnit for making HTTP calls against the running application.
I am testing a multi-step form, so I am performing several HTTP calls. Each of which produces a lot of logging, which I can access by using OutputCapture.

When doing my second HTTP call against the application, I want to access the logs produced only by/after this call. Right now, OutputCapture keeps increasing, so the first log line(s) (produced by the first HTTP call) is kept forever.
On this point, I would be very happy to have a kind of "reset"-method in OutputCapture. I would use this after having done my first HTTP call.

By the way, I have decided to use a workaround in my project:

class ResetableOutputCapture extends org.springframework.boot.test.rule.OutputCapture {
  public void reset() {
    super.releaseOutput();
    super.captureOutput();
  }
}

[philwebb]

That would seem like a nice addition. I've marked this one as ideal-for-contribution.

[snicoll]

Closing in favour of PR #8490