Move amp-beta-tester.php to root folder

amp-beta-tester.php

@@ -0,0 +1,52 @@
+<?php
+/**
+ * Plugin Name: AMP Beta Tester
+ * Description: Opt-in to receive non-stable release builds for the AMP plugin.
+ * Plugin URI: https://amp-wp.org
+ * Author: AMP Project Contributors
+ * Author URI: https://github.com/ampproject/amp-wp/graphs/contributors
+ * Version: 0.1
+ * Text Domain: amp-beta-tester
+ * Domain Path: /languages/
+ * License: GPLv2 or later
+ *
+ * @package AMP Beta Tester
+ */
+
+namespace AMP_Beta_Tester;
+
+define( 'AMP__BETA_TESTER__DIR__', dirname( __FILE__ ) );
+
+add_action( 'plugins_loaded', __NAMESPACE__ . '\init' );
+
+/**
+ * Hook into WP.
+ *
+ * @return void
+ */
+function init() {
+	// Abort init if AMP plugin is not available.
+	if ( ! defined( 'AMP__FILE__' ) ) {
+		add_action( 'admin_notices', __NAMESPACE__ . '\show_missing_amp_notice' );
+		return;
+	}
+}
+
+/**
+ * Display an admin notice if the AMP plugin is not detected.
+ *
+ * @return void
+ */
+function show_missing_amp_notice() {
+	$error = sprintf(
+		// translators: %s: AMP plugin URL.
+		esc_html__(
+			'AMP Beta Tester requires AMP to be installed and active. You can download AMP %s.',
+			'amp-beta-tester'
+		),
+		'<a href="https://amp-wp.org" target="_blank">here</a>'
+	);
+
+	// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
+	echo "<div class='notice notice-error'><p><strong>{$error}</strong></p></div>";
+}

amp.php

@@ -161,6 +161,22 @@
 	);
 }
 
+// DEV_CODE. This block of code is removed during the build process.
+if ( file_exists( AMP__DIR__ . '/amp-beta-tester.php' ) ) {
+	add_filter(
+		'site_transient_update_plugins',
+		function ( $updates ) {
+			if ( isset( $updates->response ) && is_array( $updates->response ) ) {
+				if ( array_key_exists( 'amp/amp-beta-tester.php', $updates->response ) ) {
+					unset( $updates->response['amp/amp-beta-tester.php'] );
+				}
+			}
+
+			return $updates;
+		}
+	);
+}
+
 /**
  * Displays an admin notice about why the plugin is unable to load.
  *