Allow slashes in diff paths with looks-same

[kurttomlinson]

This PR is a partial fix for #229. It creates the output diff folder immediately before asking looks-same to create a diff file. Because it only creates the folder when a diff file is going to be created, it does not create any empty folders.

This patch only applies to the looks-same differ. The Graphics Magic differ creates diff files even when there are no differences, so it needs to be fixed in a different way.

[techeverri]

I think a better approach would be to write the diff to a temp dir and then move it if there is a diff. Otherwise we'd end up with a bunch of empty directories.

Based on the comment above #229 (comment) by @oblador I would say this is not the desired behavior

[techeverri]

I would recommend you to use the workaround #229 (comment) suggested by @SebDuf using patch-package in #229

[kurttomlinson]

@techeverri I don’t think that comment applies in this case. There is an if (isSame) case above that handles when the images are the same. This newly added line of code is only executed when we already know there is a difference and a diff file needs to be created. This PR will not create any unnecessary folders.

[techeverri]

You're right @kurttomlinson 👍

[techeverri]

It would be very useful to have some kind of automated test for this fix 🤔

I'm thinking of an example project configured to have custom fileNameFormatter that uses / slashes (subfolders)

[techeverri]

BTW because of the way GitHub Actions work builds won't run when they come from forked repos (this pull request for example)
Recently I learned we shouldn't merge without running the changes through the CI pipeline

[kurttomlinson]

@techeverri I've added a spec to cover this change.

[kurttomlinson]

@techeverri Sorry to be a bother, but is there something I could do to help you review and merge this PR? 🙏

[oblador]

@kurttomlinson I've fixed so that tests run properly now 👍

[kurttomlinson]

Thanks for the fix and the merge @oblador ! 🎉

[oblador]

Thanks for the PR! I was having similar thoughts actually :-D