- Cache the output in non-persistent cache.
- Cache the result from `wp_mkdir_p()` in persistent cache (when present).
- Introduce `wp_get_upload_dir()` for use when not uploading files. It is equivalent to `wp_upload_dir()` but does not check for the existence or create the upload directory.
- Change tests to use the non-cached `_wp_upload_dir()`. They change options on the fly (should never be used in production) to simulate different environments.
- Introduce `_upload_dir_no_subdir()` and `_upload_dir_https()` to facilitate testing. These use the proper `upload_dir` filter to simulate different environments.
Props kovshenin, azaozz.
See #34359.
git-svn-id: https://develop.svn.wordpress.org/trunk@36565 602fd350-edb4-49c9-b593-d223f7449a82