diff --git a/includes/Schedule.php b/includes/Schedule.php
index f667ead..bdb4e5a 100644
--- a/includes/Schedule.php
+++ b/includes/Schedule.php
@@ -14,8 +14,8 @@
  */
 class Schedule {
 
-	const ATTACH = 'attach';
-	const DETACH = 'detach';
+	public const ATTACH = 'attach';
+	public const DETACH = 'detach';
 
 	/**
 	 * Schedule tyoe.
diff --git a/includes/Term_Manager.php b/includes/Term_Manager.php
index 1f3bf1d..f716cb0 100644
--- a/includes/Term_Manager.php
+++ b/includes/Term_Manager.php
@@ -14,6 +14,8 @@
  */
 class Term_Manager {
 
+	public const SCHEDULED_HOOK_NAME = 'schedule_terms_update_post_term_relations';
+
 	/**
 	 * Post meta key for save term info.
 	 *
@@ -49,7 +51,7 @@ public function __construct( string $post_meta_key, string $term_meta_key, int $
 		$this->time          = $time ?? time();
 		add_action( 'wp_after_insert_post', array( $this, 'update_post_term_relations' ), 100, 1 );
 		add_action( 'wp_after_insert_post', array( $this, 'update_schedule' ), 100, 1 );
-		add_action( 'schedule_terms_update_post_term_relations', array( $this, 'update_post_term_relations' ), 10, 4 );
+		add_action( self::SCHEDULED_HOOK_NAME, array( $this, 'update_post_term_relations' ), 10, 4 );
 	}
 
 	/**
@@ -63,6 +65,7 @@ private function is_active_term( ?WP_Term $term ): bool {
 		if ( ! $term ) {
 			return false;
 		}
+
 		return ! ! get_term_meta( $term->term_id, $this->term_meta_key, true );
 	}
 
@@ -139,8 +142,8 @@ public function update_schedule( int $post_id ) {
 			if ( ! $schedule->is_expired( $this->time ) ) {
 				$time   = $schedule->get_timestamp();
 				$params = array( $post_id, array( $schedule->get_type() ), $schedule->get_taxonomy(), $schedule->get_term() );
-				wp_clear_scheduled_hook( 'schedule_terms_update_post_term_relations', $params );
-				wp_schedule_single_event( $time, 'schedule_terms_update_post_term_relations', $params );
+				wp_clear_scheduled_hook( self::SCHEDULED_HOOK_NAME, $params );
+				wp_schedule_single_event( $time, self::SCHEDULED_HOOK_NAME, $params );
 			}
 		}
 	}
diff --git a/tests/Term_Manager_Test.php b/tests/Term_Manager_Test.php
index 3492ee9..4804efa 100644
--- a/tests/Term_Manager_Test.php
+++ b/tests/Term_Manager_Test.php
@@ -8,7 +8,6 @@
 namespace HAMWORKS\WP\Schedule_Terms\Tests;
 
 use HAMWORKS\WP\Schedule_Terms\Term_Manager;
-use PHPUnit\Framework\TestCase;
 use WP_UnitTestCase;
 
 /**
@@ -20,7 +19,7 @@ class Term_Manager_Test extends WP_UnitTestCase {
 	 * Test for Term_Manager::update_post_term_relations().
 	 */
 	public function test_update_post_term_relations() {
-		$term_manager = new Term_Manager( 'schedule_terms', 'schedule_terms_active' );
+		$term_manager = new Term_Manager( 'schedule_terms', 'schedule_terms_active', strtotime( '2022-05-29T08:05:41+00:00' ) );
 
 		$category_id = $this->factory()->category->create( array( 'name' => 'category-1' ) );
 		update_term_meta( $category_id, 'schedule_terms_active', true );
@@ -33,22 +32,125 @@ public function test_update_post_term_relations() {
 				'type'     => 'attach',
 				'taxonomy' => 'category',
 				'term'     => 'category-1',
-				'datetime' => '2012-07-05T22:09:28+09:00',
+				'datetime' => '2020-07-05T22:09:28+09:00',
 			),
 			false
 		);
 
+		add_post_meta(
+			$post_id,
+			'schedule_terms',
+			array(
+				'type'     => 'detach',
+				'taxonomy' => 'category',
+				'term'     => 'category-1',
+				'datetime' => '2022-07-05T22:09:28+09:00',
+			),
+			false
+		);
 
 		$term_manager->update_post_term_relations( $post_id );
-
 		$this->assertTrue( has_category( 'category-1', $post_id ) );
+
+		$reflection = new \ReflectionClass( $term_manager );
+		$time       = $reflection->getProperty( 'time' );
+		$time->setAccessible( true );
+		$time->setValue( $term_manager, strtotime( '2023-05-29T08:05:41+00:00' ) );
+		$term_manager->update_post_term_relations( $post_id );
+		$this->assertFalse( has_category( 'category-1', $post_id ) );
 	}
 
 	/**
 	 * Test for Term_Manager::update_schedule().
 	 */
 	public function test_update_schedule() {
-		$this->assertEquals( 1, 1 );
+		$term_manager = new Term_Manager( 'schedule_terms', 'schedule_terms_active', strtotime( '2022-05-29T08:05:41+00:00' ) );
+
+		foreach ( range( 1, 2 ) as $index ) {
+			$category_id = $this->factory()->category->create( array( 'name' => 'category-' . $index ) );
+			update_term_meta( $category_id, 'schedule_terms_active', true );
+		}
+
+		$post_id = $this->factory()->post->create();
+		add_post_meta(
+			$post_id,
+			'schedule_terms',
+			array(
+				'type'     => 'attach',
+				'taxonomy' => 'category',
+				'term'     => 'category-1',
+				'datetime' => '2022-05-29T08:05:40+00:00',
+			),
+			false
+		);
+		add_post_meta(
+			$post_id,
+			'schedule_terms',
+			array(
+				'type'     => 'detach',
+				'taxonomy' => 'category',
+				'term'     => 'category-1',
+				'datetime' => '2022-05-29T08:05:42+00:00',
+			),
+			false
+		);
+		add_post_meta(
+			$post_id,
+			'schedule_terms',
+			array(
+				'type'     => 'attach',
+				'taxonomy' => 'category',
+				'term'     => 'category-2',
+				'datetime' => '2022-05-29T08:05:42+00:00',
+			),
+			false
+		);
+		add_post_meta(
+			$post_id,
+			'schedule_terms',
+			array(
+				'type'     => 'detach',
+				'taxonomy' => 'category',
+				'term'     => 'category-2',
+				'datetime' => '2022-05-29T08:05:43+00:00',
+			),
+			false
+		);
+		$term_manager->update_schedule( $post_id );
+
+		$events = array_filter(
+			self::get_events(),
+			function ( $event ) {
+				return Term_Manager::SCHEDULED_HOOK_NAME === $event->hook;
+			}
+		);
+
+		$this->assertEquals( 3, count( $events ) );
+	}
+
+	/**
+	 * Get events.
+	 *
+	 * @return array
+	 */
+	public static function get_events(): array {
+		$crons  = _get_cron_array();
+		$events = array();
+		foreach ( $crons as $time => $hooks ) {
+			foreach ( $hooks as $hook => $hook_events ) {
+				foreach ( $hook_events as $sig => $data ) {
+					$events[] = (object) array(
+						'hook'     => $hook,
+						'time'     => $time,
+						'sig'      => $sig,
+						'args'     => $data['args'],
+						'schedule' => $data['schedule'],
+					);
+				}
+			}
+		}
+
+		return $events;
 	}
 
 }