Ticket #42597: 42597.1.diff

src/wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php

@@ -419 +419 @@
                         if ( $term_id = $term->get_error_data( 'term_exists' ) ) {
                                 $existing_term = get_term( $term_id, $this->taxonomy );
                                 $term->add_data( $existing_term->term_id, 'term_exists' );
-                                $term->add_data( array( 'status' => 409 ) );
+                                $term->add_data( array( 'status' => 409, 'term_id' => $term_id ) );
                         }
 
                         return $term;

tests/phpunit/tests/rest-api/rest-categories-controller.php

@@ -696 +696 @@
          */
         public function test_create_item_term_already_exists() {
                 wp_set_current_user( self::$administrator );
+                $existing_id = $this->factory->category->create( array( 'name' => 'Existing' ) );
+
                 $request = new WP_REST_Request( 'POST', '/wp/v2/categories' );
-                $request->set_param( 'name', 'test' );
+                $request->set_param( 'name', 'Existing' );
+
                 $response = $this->server->dispatch( $request );
-                $this->assertEquals( 201, $response->get_status() );
-                $response = $this->server->dispatch( $request );
                 $this->assertEquals( 409, $response->get_status() );
                 $data = $response->get_data();
                 $this->assertEquals( 'term_exists', $data['code'] );
+                $this->assertEquals( $existing_id, (int) $data['data']['term_id'] );
+
+                wp_delete_term( $existing_id, 'category' );
         }
 
         public function test_create_item_invalid_taxonomy() {