Allow regular expression parsing if the redirect target is a valid URL

[benlk]

Description of the Change

#269 reported a bug in the handling of regex redirects with a URL target: the URLs were being prefixed with a /.

#279 fixed #269 by excluding the section of code that prepends URLs with / from being applied if the redirect target was a valid URL:

safe-redirect-manager/inc/classes/class-srm-redirect.php

Lines 225 to 229 in cb1c045

	// Allow for regex replacement in $redirect_to
	if ( $enable_regex && ! filter_var( $redirect_to, FILTER_VALIDATE_URL ) ) {
	$redirect_to = preg_replace( '@' . $redirect_from . '@' . $regex_flag, $redirect_to, $requested_path );
	$redirect_to = '/' . ltrim( $redirect_to, '/' );
	}

Unfortunately, this also excluded the code that applies the regular expression to the redirect target URL. If the redirect target was a URL, the final preg_replace was no longer applied.

This fix separates the prefix-with-/ behavior from regex parsing by separating the conditionals.

Closes #380

How to test the Change

Test cases, all with regular expressions:

• from /test/(.*) to https://example.org/$1 with /test/1234 should go to https://example.org/1234/ (Regex pattern replacement fails if destination is absolute url. #380)
• from /test/(.*) to /$1 with /test/1234/ should go to /1234/
• from (go|be)\/h{0,}$ to /404-regex with /be/hhhh should go to /404-regex (Regex redirects without leading / are buggy #269)
• from (go|be)\/h{0,}$ to http://xu-osp-plugins.local/404-regex with /be/hhhh should go to http://xu-osp-plugins.local/404-regex (Regex redirects without leading / are buggy #269)

Changelog Entry

Fixed - Allows use of full URLs as redirect targets when using absolute URLs (#395 for #380)

Credits

Props @benlk @peterwilsoncc

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added Critical Flows, Test Cases, and/or End-to-End Tests to cover my change.
• All new and existing tests pass.

[github-actions]

@benlk thanks for the PR! Could you please fill out the PR template with description, changelog, and credits information so that we can properly review and merge this?

[peterwilsoncc]

@benlk I took some liberties while testing this out.

I re-ordered the commits to make sure the tests were failing against the unchanged code but they were passing, see the action run.

I subsequently pushed some failing tests in 30c4c84, which did fail against the unchanged code, see the action run

I finally pushed the fix (the new commit hash is 5e7bb7e) and the action is now passing, see the action run

So... Are you able to confirm my updates to the test are testing the correct things? I'll review the changes in the mean time.

[peterwilsoncc]

These changes look good to me, I think this is good to merge once Ben validates my updates to the tests.

[benlk]

The changes look good to me as well. The revised tests appear to be testing what was intended.

[peterwilsoncc]

I have no idea why the validation bot is failing to pick up the descriptions so ignoring the issue and merging regardless.