From cc1c0639d0dc9a0fdb6e28f41c1601693e05afc0 Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Thu, 30 Mar 2017 16:49:47 +0000
Subject: [PATCH] Invalidate term query caches when setting or deleting term
 relationships.

Prior to 4.7, term relationships - as set by `wp_set_object_terms()` or
`wp_remove_object_terms()` - did not affect the term query cache. The
introduction of the 'object_ids' parameter in 4.7 means that the query
cache must be aware of object-term relationships. As such, the
'last_changed' incrementor is now invalidated when term relationships
are modified.

This bug only reared its head when delaying term counting, because term
counting performs its own term query cache invalidation.

Props mboynes.
Fixes #40306.

git-svn-id: https://develop.svn.wordpress.org/trunk@40353 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/taxonomy.php             |  2 +
 tests/phpunit/tests/term/getTheTerms.php | 62 ++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index 9ebc9d0d0b..94f36689fd 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -2282,6 +2282,7 @@ function wp_set_object_terms( $object_id, $terms, $taxonomy, $append = false ) {
 	}
 
 	wp_cache_delete( $object_id, $taxonomy . '_relationships' );
+	wp_cache_delete( 'last_changed', 'terms' );
 
 	/**
 	 * Fires after an object's terms have been set.
@@ -2376,6 +2377,7 @@ function wp_remove_object_terms( $object_id, $terms, $taxonomy ) {
 		$deleted = $wpdb->query( $wpdb->prepare( "DELETE FROM $wpdb->term_relationships WHERE object_id = %d AND term_taxonomy_id IN ($in_tt_ids)", $object_id ) );
 
 		wp_cache_delete( $object_id, $taxonomy . '_relationships' );
+		wp_cache_delete( 'last_changed', 'terms' );
 
 		/**
 		 * Fires immediately after an object-term relationship is deleted.
diff --git a/tests/phpunit/tests/term/getTheTerms.php b/tests/phpunit/tests/term/getTheTerms.php
index 6a3d4ba5c1..1bffcb6a63 100644
--- a/tests/phpunit/tests/term/getTheTerms.php
+++ b/tests/phpunit/tests/term/getTheTerms.php
@@ -191,4 +191,66 @@ class Tests_Term_GetTheTerms extends WP_UnitTestCase {
 		$this->assertSame( $num_queries, $wpdb->num_queries );
 
 	}
+
+	/**
+	 * @ticket 40306
+	 */
+	public function test_term_cache_should_be_invalidated_on_set_object_terms() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		// Temporarily disable term counting, which performs its own cache invalidation.
+		wp_defer_term_counting( true );
+
+		// Create Test Category.
+		$term_id = self::factory()->term->create( array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		$post_id = self::factory()->post->create();
+
+		// Prime cache.
+		get_the_terms( $post_id, 'wptests_tax' );
+
+		wp_set_object_terms( $post_id, $term_id, 'wptests_tax' );
+
+		$terms = get_the_terms( $post_id, 'wptests_tax' );
+
+		// Re-activate term counting so this doesn't affect other tests.
+		wp_defer_term_counting( false );
+
+		$this->assertTrue( is_array( $terms ) );
+		$this->assertSame( array( $term_id ), wp_list_pluck( $terms, 'term_id' ) );
+	}
+
+	/**
+	 * @ticket 40306
+	 */
+	public function test_term_cache_should_be_invalidated_on_remove_object_terms() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		// Create Test Category.
+		$term_ids = self::factory()->term->create_many( 2, array(
+			'taxonomy' => 'wptests_tax',
+		) );
+
+		$post_id = self::factory()->post->create();
+
+		wp_set_object_terms( $post_id, $term_ids, 'wptests_tax' );
+
+		// Prime cache.
+		get_the_terms( $post_id, 'wptests_tax' );
+
+		// Temporarily disable term counting, which performs its own cache invalidation.
+		wp_defer_term_counting( true );
+
+		wp_remove_object_terms( $post_id, $term_ids[0], 'wptests_tax' );
+
+		$terms = get_the_terms( $post_id, 'wptests_tax' );
+
+		// Re-activate term counting so this doesn't affect other tests.
+		wp_defer_term_counting( false );
+
+		$this->assertTrue( is_array( $terms ) );
+		$this->assertSame( array( $term_ids[1] ), wp_list_pluck( $terms, 'term_id' ) );
+	}
 }