Add wp cache flush-group for flushing a cache group (#85)

* Added group flushing.

Needs extra input for testing.

* Added failsafe for older WP versions.

Also phpcs formatting.

* Processed feedback.

* Added test for error on clear-group

* Renamed clear-group to flush-group

Fixed failing test and generated readme file.

* Set correct error message in the test.

* Make sure a test only runs at 6.1 or later.

Author: janw-me

README.md

@@ -164,6 +164,27 @@ Errors if the object cache can't be flushed.
 
 
 
+### wp cache flush-group
+
+Removes all cache items in a group, if the object cache implementation supports it.
+
+~~~
+wp cache flush-group <group>
+~~~
+
+**OPTIONS**
+
+	<group>
+		Cache group key.
+
+**EXAMPLES**
+
+    # Clear cache group.
+    $ wp cache flush-group my_group
+    Success: Cache group 'my_group' was flushed.
+
+
+
 ### wp cache get
 
 Gets a value from the object cache.

composer.json

@@ -37,6 +37,7 @@
             "cache decr",
             "cache delete",
             "cache flush",
+            "cache flush-group",
             "cache get",
             "cache incr",
             "cache replace",

features/cache.feature

@@ -133,6 +133,59 @@ Feature: Managed the WordPress object cache
       Error: Could not replace object 'bar' in group 'foo'. Does it not exist?
       """
 
+  @require-wp-6.1
+  Scenario: Some cache groups cannot be cleared.
+    Given a WP install
+    When I run `wp cache flush-group add_multiple`
+    Then STDOUT should be:
+      """
+      Success: Cache group 'add_multiple' was flushed.
+      """
+
+  @require-wp-6.1
+  Scenario: Some cache groups cannot be cleared.
+    Given a WP install
+    And a wp-content/mu-plugins/unclearable-test-cache.php file:
+      """php
+      <?php
+      class Dummy_Object_Cache extends WP_Object_Cache {
+        public function flush_group( $group ) {
+          if ( $group === 'permanent_root_cache' ) {
+            return false;
+          }
+          return parent::flush_group( $group );
+        }
+      }
+      $GLOBALS['wp_object_cache'] = new Dummy_Object_Cache();
+      """
+    When I try `wp cache flush-group permanent_root_cache`
+    Then STDERR should be:
+      """
+      Error: Cache group 'permanent_root_cache' was not flushed.
+      """
+
+  @less-than-wp-6.1
+  Scenario: Some cache groups cannot be cleared.
+    Given a WP install
+    And a wp-content/mu-plugins/unclearable-test-cache.php file:
+      """php
+      <?php
+      class Dummy_Object_Cache extends WP_Object_Cache {
+        public function flush_group( $group ) {
+          if ( $group === 'permanent_root_cache' ) {
+            return false;
+          }
+          return parent::flush_group( $group );
+        }
+      }
+      $GLOBALS['wp_object_cache'] = new Dummy_Object_Cache();
+      """
+    When I try `wp cache flush-group permanent_root_cache`
+    Then STDERR should be:
+      """
+      Error: Group flushing is not supported.
+      """
+
   Scenario: Flushing cache on a multisite installation
     Given a WP multisite installation
 

src/Cache_Command.php

@@ -378,4 +378,33 @@ public function supports( $args, $assoc_args ) {
 		WP_CLI::halt( 1 );
 	}
 
+	/**
+	 * Removes all cache items in a group, if the object cache implementation supports it.
+	 *
+	 * ## OPTIONS
+	 *
+	 * <group>
+	 * : Cache group key.
+	 *
+	 * ## EXAMPLES
+	 *
+	 *     # Clear cache group.
+	 *     $ wp cache flush-group my_group
+	 *     Success: Cache group 'my_group' was flushed.
+	 *
+	 * @subcommand flush-group
+	 */
+	public function flush_group( $args, $assoc_args ) {
+		list( $group ) = $args;
+
+		if ( ! function_exists( 'wp_cache_supports' ) || ! wp_cache_supports( 'flush_group' ) ) {
+			WP_CLI::error( 'Group flushing is not supported.' );
+		}
+
+		if ( ! wp_cache_flush_group( $group ) ) {
+			WP_CLI::error( "Cache group '$group' was not flushed." );
+		}
+		WP_CLI::success( "Cache group '$group' was flushed." );
+	}
+
 }