Add create-embed-test-post script and fix support for various embeds

.dev-lib

@@ -1,2 +1,6 @@
 SYNC_README_MD=0
 PATH_EXCLUDES_PATTERN=includes/lib/*
+
+if [[ ${TRAVIS_PHP_VERSION:0:3} == "5.2" ]]; then
+	PATH_EXCLUDES_PATTERN="$PATH_EXCLUDES_PATTERN,bin/create-embed-test-post.php"
+fi

bin/create-embed-test-post.php

@@ -0,0 +1,77 @@
+<?php
+/**
+ * Create embed test post.
+ *
+ * @package AMP
+ */
+
+if ( ! defined( 'WP_CLI' ) ) {
+	echo "Must be run in WP-CLI via: wp eval-file bin/create-embed-test-post.php\n";
+	exit( 1 );
+}
+
+$data_entries = array(
+	array(
+		'prepare' => 'amp_test_prepare_image_attachments',
+		'heading' => 'Media Gallery',
+		'content' => function( $data ) {
+			return sprintf( '[gallery ids="%s"]', implode( ',', $data['ids'] ) );
+		},
+	),
+);
+
+/**
+ * Prepare test by ensuring attachments exist.
+ *
+ * @param array $data Entry data.
+ * @return array Data.
+ */
+function amp_test_prepare_image_attachments( $data ) {
+	$attachments = get_children( array(
+		'post_parent' => 0,
+		'post_status' => 'inherit',
+		'post_type' => 'attachment',
+		'post_mime_type' => 'image',
+	) );
+	$data['ids'] = wp_list_pluck( $attachments, 'ID' );
+
+	// @todo Add some attachments if count( $data['ids'] ) < 5.
+	return $data;
+}
+
+// Run the script.
+$page = get_page_by_path( '/amp-test-embeds/' );
+if ( $page ) {
+	$page_id = $page->ID;
+} else {
+	$page_id = wp_insert_post( array(
+		'post_name' => 'amp-test-embeds',
+		'post_title' => 'AMP Test Embeds',
+		'post_type' => 'page',
+	) );
+}
+
+$content = '';
+foreach ( $data_entries as $data_entry ) {
+	if ( isset( $data_entry['prepare'] ) ) {
+		$data_entry = array_merge(
+			$data_entry,
+			call_user_func( $data_entry['prepare'], $data_entry )
+		);
+	}
+
+	$content .= sprintf( "<h1>%s</h1>\n", $data_entry['heading'] );
+	if ( is_callable( $data_entry['content'] ) ) {
+		$content .= call_user_func( $data_entry['content'], $data_entry );
+	} else {
+		$content .= $data_entry['content'];
+	}
+	$content .= "\n\n";
+}
+
+wp_update_post( wp_slash( array(
+	'ID' => $page_id,
+	'post_content' => $content,
+) ) );
+
+WP_CLI::success( sprintf( 'Please take a look at: %s', get_permalink( $page_id ) ) );