public function test_not_has_filter_with_directly_removed_callback() {
    $callback      = '__return_null';
    $hook          = new WP_Hook();
    $tag           = __FUNCTION__;
    $priority      = rand( 1, 100 );
    $accepted_args = rand( 1, 100 );

    $hook->add_filter( $tag, $callback, $priority, $accepted_args );
    $function_key = _wp_filter_build_unique_id( $tag, $callback, $priority );
    unset( $hook->callbacks[ $priority ][ $function_key ] );

    $this->assertFalse( $hook->has_filters() );
  }