Basic CPT plugin

testcpt.php

<?php
/**
 * Test CPT with TT2.
 *
 * Plugin Name: Test CPT
 * Plugin URI:  https://github.com/tester/testcpt/
 * Description: Tests custom post type blank screen with TT2
 * Version:     1.0
 * Author:      tester
 * Author URI:  https://github.com/tester/testcpt/
 * License:     GPLv2 or later
 * License URI: http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * Text Domain: testcpt
 * Domain Path: /languages
 * Requires at least: 4.9
 * Requires PHP: 5.6 or later
 */
namespace TestCPT;

if ( ! defined( 'ABSPATH' ) ) {
	die( 'Invalid request.' );
}


function register_custom_post_type() {
	register_post_type( 'testcpt',
		array(
			'labels'      => array(
				'name'          => __( 'TestCPT', 'testcpt' ),
				'singular_name' => __( 'TestCPT', 'testcpt' ),
			),
			'public'      => true,
			'has_archive' => true,
			'show_in_rest' => true,
			'rewrite'     => array( 'slug' => 'testcpt' )
		)
	);
}
add_action( 'init', __NAMESPACE__ . '\register_custom_post_type' );