Fix broken category links when removing category base

[philipjohn]

Description

Calls to get_term_link() and get_category_link() should always return a full URL, but wpcom_vip_load_category_base() has been breaking that behaviour. This fix restores the correct functioning by using home_url() to ensure there is a full URL.

Fixes #4541

Changelog Description

Fix broken category links when removing category base

Calls to get_term_link() and get_category_link() should always return a full URL, but wpcom_vip_load_category_base() has been breaking that behaviour. This fix restores the correct functioning by using home_url() to ensure there is a full URL.

Pre-review checklist

Please make sure the items below have been covered before requesting a review:

• This change works and has been tested locally (or has an appropriate fallback).
• This change works and has been tested on a Go sandbox.
• This change has relevant unit tests (if applicable).
• This change uses a rollout method to ease with deployment (if applicable - especially for large scale actions that require writes).
• This change has relevant documentation additions / updates (if applicable).
• I've created a changelog description that aligns with the provided examples.

Pre-deploy checklist

• VIP staff: Ensure any alerts added/updated conform to internal standards (see internal documentation).

Steps to Test

1. Using WP-CLI or theme code, call get_category_link(CATEGORYID) with a valid category ID and note the absolute URL.
2. Add wpcom_vip_load_category_base(''); to the themes function file or an mu-plugin.
3. Repeat step 1 and note that you now get a relative URL returned instead of an absolute one.
4. Apply this patch and repeat step 1 and observe you now have a full URL again

[codecov]

Codecov Report

Merging #4922 (ed0b0c8) into develop (90bd992) will decrease coverage by 3.13%.
Report is 794 commits behind head on develop.
The diff coverage is 0.00%.

@@              Coverage Diff              @@
##             develop    #4922      +/-   ##
=============================================
- Coverage      32.29%   29.17%   -3.13%     
- Complexity      3771     4744     +973     
=============================================
  Files            226      278      +52     
  Lines          16807    20887    +4080     
=============================================
+ Hits            5428     6093     +665     
- Misses         11379    14794    +3415     

Files	Coverage Δ
vip-helpers/vip-permastructs.php	0.00% <0.00%> (ø)

... and 177 files with indirect coverage changes

[WPprodigy]

Hey Phillip 😃 !

Thanks for the patch. I'll give this some testing just to make sure there won't be any unexpected side-effects.

As an aside, I rather would like to deprecate the wpcomvip-era custom rewrite rules eventually. Some context in this issue, such as: #1141 (comment)

[WPprodigy]

Setting an empty string as the category base via wpcom_vip_load_category_base( '' ) doesn't seem to really work for me as far as actually loading a category page - WP doesn't seem to find the route. Same with wpcom_vip_load_tag_base( '' );, except it won't even respect the empty string and still defaults to /tag.

That said, I can see the issue with direct function calls like get_category_link(10, 'category'). Tested both child and parent categories and the patch does seem sound. Confirmed that get_term_link() uses home_url() in the same way.