Appending hyphen before numbers when creating a create unique filename in wp_unique_filename()

[husobj]

When WordPress appends a number to a file to create a unique filename, it just adds a number to the file.
ie If "photo.jpg" exists then "photo1.jpg" is created

I suggest that it should include a hyphen so the file would be called "photo-1.jpg"

The main reason is that if you upload files ending in numbers then then the new filename is less easy to read.
ie If "photo234.jpg" exists then "photo2341.jpg" is created

Would be nicer if it produced "photo234-1.jpg"

It's only cosmetic but it does make it easier to search for images in the uploads folder if you need to for any reason, especially if you have uploaded a load of images from a camera DSC123.jpg, DSC124.jpg etc

[c3mdigital]

+1 for consistency with wp_unique_post_slug() and wp_uniquie_term_slug()

[mikejolley]

Patch to append hyphens e.g. IMAGE-1.jpg instead of IMAGE1.jpg

[mikejolley]

I've attached a patch for this. It will ensure appended numbers are prepended with a hyphen.

Works with both the extension case logic, when extension is non existent, and regular filenames.

[tyxla]

Altering Tests_Functions::test_wp_unique_filename() to support the hyphen prefix when creating unique filenames

[tyxla]

I think that in terms of unit tests, this only requires a modification to Tests_Functions::test_wp_unique_filename() in order to support the new unique naming scheme.

@wonderboymusic do you think there are additional cases that should be covered?

[wonderboymusic]

In 35276:

Formatting: when making unique filenames in wp_unique_filename() by adding an incrementing number, prefix it with a dash to disambiguate from files that end in numbers.

Updates unit tests.

Props mikejolley, tyxla.
Fixes #21453.