Taxonomy: in get_terms(), do not assume that legacy args are being passed when the only params are top-level meta_* values. Add keys in WP_Term_Query::__construct().

Adds unit tests.

Props flixos90, boonebgorges.
Fixes #37568.


git-svn-id: https://develop.svn.wordpress.org/trunk@38337 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-term-query.php

@@ -208,6 +208,10 @@ class WP_Term_Query {
 			'cache_domain'           => 'core',
 			'update_term_meta_cache' => true,
 			'meta_query'             => '',
+			'meta_key'               => '',
+			'meta_value'             => '',
+			'meta_type'              => '',
+			'meta_compare'           => '',
 		);
 
 		if ( ! empty( $query ) ) {

tests/phpunit/tests/term/getTerms.php

@@ -11,6 +11,29 @@ class Tests_Term_getTerms extends WP_UnitTestCase {
 		wp_cache_delete( 'last_changed', 'terms' );
 	}
 
+	/**
+	 * @ticket 37568
+	 */
+	public function test_meta_query_args_only() {
+		register_taxonomy( 'wptests_tax', 'post', array( 'hierarchical' => true ) );
+
+		$term1 = self::factory()->term->create( array( 'taxonomy' => 'wptests_tax' ) );
+		$term2 = self::factory()->term->create( array( 'taxonomy' => 'wptests_tax' ) );
+
+		$post = self::factory()->post->create( array( 'post_type' => 'post' ) );
+
+		update_term_meta( $term1, 'somekey', 'thevalue' );
+
+		wp_set_post_terms( $post, array( $term1, $term2 ), 'wptests_tax' );
+
+		$found = get_terms( array(
+			'meta_key' => 'somekey',
+			'meta_value' => 'thevalue',
+		) );
+
+		$this->assertEqualSets( array( $term1 ), wp_list_pluck( $found, 'term_id' ) );
+	}
+
 	/**
 	 * @ticket 35495
 	 */