support banner/footer option

src/Bundle.js

@@ -337,6 +337,9 @@ export default class Bundle {
 			indentString: getIndentString( magicString, options )
 		}, options );
 
+		if ( options.banner ) magicString.prepend( options.banner + '\n' );
+		if ( options.footer ) magicString.append( '\n' + options.footer );
+
 		const code = magicString.toString();
 		let map = null;
 

test/form/banner-and-footer/_config.js

@@ -0,0 +1,7 @@
+module.exports = {
+	description: 'adds a banner/footer',
+	options: {
+		banner: '/* this is a banner */',
+		footer: '/* this is a footer */'
+	}
+};

test/form/banner-and-footer/_expected/amd.js

@@ -0,0 +1,7 @@
+/* this is a banner */
+define(function () { 'use strict';
+
+	console.log( 'hello world' );
+
+});
+/* this is a footer */

test/form/banner-and-footer/_expected/cjs.js

@@ -0,0 +1,5 @@
+/* this is a banner */
+'use strict';
+
+console.log( 'hello world' );
+/* this is a footer */

test/form/banner-and-footer/_expected/es6.js

@@ -0,0 +1,3 @@
+/* this is a banner */
+console.log( 'hello world' );
+/* this is a footer */

test/form/banner-and-footer/_expected/iife.js

@@ -0,0 +1,7 @@
+/* this is a banner */
+(function () { 'use strict';
+
+	console.log( 'hello world' );
+
+})();
+/* this is a footer */

test/form/banner-and-footer/_expected/umd.js

@@ -0,0 +1,11 @@
+/* this is a banner */
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory() :
+	typeof define === 'function' && define.amd ? define(factory) :
+	factory();
+}(this, function () { 'use strict';
+
+	console.log( 'hello world' );
+
+}));
+/* this is a footer */

test/form/banner-and-footer/main.js

@@ -0,0 +1 @@
+console.log( 'hello world' );