I understand how to send slack notifications in a Pipeline script on success, or on failure. This is useful for build jobs.

For automated tests, a notification on each job is not so useful. Instead, I'd rather be notified when a job fails, or when a job succeeds and the previous job failed. Pre-Pipeline, this was referred to as "Back to normal" I think.

I'd like a way to know that a previous build failed. Something like this:

[... test completed successfully]
if (previousBuild.success() == false) {
   [send slack message: "Test back to normal]
}