Check for wp_cache_flush_group() before calling it - #129

The johnbillion/wp-compat PHPStan extension that now ships with wp-cli-tests reported a single error for this package:

src/Cache_Command.php:432  wp_cache_flush_group() is only available since WordPress version 6.1.0.

wp cache flush-group guarded that call like this:

if ( ! function_exists( 'wp_cache_supports' ) || ! wp_cache_supports( 'flush_group' ) ) {
    WP_CLI::error( 'Group flushing is not supported.' );
}

if ( ! wp_cache_flush_group( $group ) ) {

wp_cache_supports() and wp_cache_flush_group() both arrived in WordPress 6.1, so the version question was already covered and this is not a compatibility bug against the 4.9 baseline. But the guard tests a different function than the one being called, and that gap is not purely theoretical: wp_cache_supports() is answered by the object cache drop-in, and a drop-in that reports flush_group support without defining wp_cache_flush_group() would produce a fatal instead of the intended error message.

So rather than adding an ignore entry, the condition now also checks for the function it actually calls. That closes the drop-in gap and, since function_exists() is a guard wp-compat understands, resolves the error at the same time — this package needs no wp-compat ignores at all.

Behaviour

Unchanged everywhere it can be observed. On WordPress 6.1+ the function exists, so the added check is always true and the guard behaves exactly as before. Below 6.1 the command already errored with the same message. The difference only shows up for a drop-in that advertises support it does not implement, where a fatal becomes Error: Group flushing is not supported.

Tests

No changes. The existing flush-group scenarios in features/cache.feature are tagged @require-wp-6.1 and continue to pass unaffected, since the added condition is always satisfied there.

Verification

Run locally against the same dependency versions CI resolves (johnbillion/wp-compat 2.0.0, php-stubs/wordpress-stubs v6.9.4, wp-cli/wp-cli-tests v5.2.3):

• composer phpstan — [OK] No errors
• composer phpcs — clean
• php -l — clean

GitHub Actions was failing to allocate runners across the org while this was written, so CI may need a re-run once that clears.

Generated by Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved compatibility with environments that do not provide group cache-flushing support.
  • Returns the existing error instead of attempting an unavailable cache operation.