constructor method

function __construct() {
    add_action( 'admin_print_scripts-widgets.php', function(){
        if (is_admin()){ //test fails b/c the admin_print_scripts-widget.php is not aware that is_admin() is true...
            wp_enqueue_style( 'spw-admin', plugins_url( 'css/' . 'spw-admin.min.css', dirname( __FILE__ ) ), false, 1 );
            wp_enqueue_script( 'spw-admin', plugins_url( 'javascripts/' . 'spw-admin.min.js', dirname( __FILE__ ) ), array( 'jquery' ), 1, true );
        }
    } );
}

test

	function testSpwScriptsLoaded() {
 
	    $this->assertFalse( wp_script_is( 'spw-admin' ) );
	    do_action( 'admin_print_scripts-widgets.php' );
	    $this->assertTrue( wp_script_is( 'spw-admin' ) );
 
	}