Clean up after successful test run

[kot-lex]

trafficstars

Wouldn't it be more useful if we will delete .new.png and .diff.png for the successful tests? Current approach requires running approve command every time even if all screenshots match the reference ones.

[unindented]

if all screenshots match the reference ones

Why do you need to approve if they're the same?

[kot-lex]

Just to prevent them from being accidentally committed into repo. Another solution is to add *.diff.png and *.new.png into .gitignore, but what is the use of those files in case tests were passed?

[unindented]

Ah, we do have those files in our .gitignore, that's probably why this was a non-issue for us.

I'm open to merging a PR that removes those files after successful run though.