public function __construct( $args = array() ) {

		// Accept just a string prefix for convenience.
		if ( is_string( $args ) ) {
			$args = array( 'prefix' => $args );
		}

		$defaults = array(
			'prefix'            => '',
			'notifications_url' => '',
			'version'           => '',
		);
		$args     = wp_parse_args( $args, $defaults );

		if ( ! $args['prefix'] || ! $args['notifications_url'] || ! $args['version'] ) {
			throw new Exception( 'Missing required arguments: prefix, version and/or notifications_url.' );
		}

		$this->prefix            = sanitize_key( $args['prefix'] );
		$this->version           = sanitize_title( $args['version'] );
		$this->notifications_url = sanitize_url( $args['notifications_url'] );

		add_action( "wp_ajax_{$this->prefix}_notifications", array( $this, 'notifications' ) );

		add_action( "wp_ajax_{$this->prefix}_hide_notice", array( $this, 'hide_notice' ) );

		// Add filters for standard checks.
		add_filter( "{$this->prefix}_notification_test_plugins_active", array( $this, 'notification_test_plugins_active' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_check_plugin_version", array( $this, 'notification_test_check_plugin_version' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_pmpro_license", array( $this, 'notification_test_pmpro_license' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_pmpro_num_members", array( $this, 'notification_test_pmpro_num_members' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_pmpro_num_levels", array( $this, 'notification_test_pmpro_num_levels' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_pmpro_num_discount_codes", array( $this, 'notification_test_pmpro_num_discount_codes' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_pmpro_revenue", array( $this, 'notification_test_pmpro_revenue' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_pmpro_num_orders", array( $this, 'notification_test_pmpro_num_orders' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_pmpro_setting", array( $this, 'notification_test_pmpro_setting' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_llms_setting", array( $this, 'notification_test_llms_setting' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_llms_revenue", array( $this, 'notification_test_llms_revenue' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_llms_num_orders", array( $this, 'notification_test_llms_num_orders' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_site_url_match", array( $this, 'notification_test_site_url_match' ), 10, 2 );
		add_filter( "{$this->prefix}_notification_test_check_option", array( $this, 'notification_test_check_option' ), 10, 2 );
	}