Clarified IIFE Wrapper Derived Configuration (#7)

Author: kristoferbaxter

src/index.ts

@@ -28,17 +28,25 @@ export const defaultCompileOptions = (outputOptions: OutputOptions): CompileOpti
   // - When Rollup is configured to output an iife, ensure Closure Compiler does not
   // mangle the name of the iife wrapper.
 
+  let externs: string = `
+/**
+ * @fileoverview Externs built via derived configuration from Rollup or input code.
+ * @externs
+ */`;
+
   const options: CompileOptions = {
     language_out: 'NO_TRANSPILE',
     assume_function_wrapper: outputOptions.format === 'es' ? true : false,
     warning_level: 'QUIET',
   };
   if (outputOptions.format === 'iife' && outputOptions.name) {
-    options['externs'] = sync(`function ${outputOptions.name}(){}`);
+    externs = `${externs}\nvar ${outputOptions.name} = function(){};`;
+
+    options['externs'] = sync(externs);
   }
 
   return options;
-}
+};
 
 export default function closureCompiler(compileOptions: CompileOptions = {}): Plugin {
   return {
@@ -58,11 +66,7 @@ export default function closureCompiler(compileOptions: CompileOptions = {}): Pl
       });
 
       const compile: Promise<string> = new Promise((resolve, reject) => {
-        new compiler(compileOptions).run((
-          exitCode: number,
-          stdOut: string,
-          stdErr: string,
-        ) => {
+        new compiler(compileOptions).run((exitCode: number, stdOut: string, stdErr: string) => {
           if (exitCode !== 0) {
             reject(new Error(`Google Closure Compiler exit ${exitCode}: ${stdErr}`));
           } else {

test/iife-wrapped-safely.js

@@ -0,0 +1,39 @@
+/**
+ * Copyright 2018 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import test from 'ava';
+import compiler from '../dist/index';
+import { rollup } from 'rollup';
+import { readFileSync } from 'fs';
+import { join } from 'path';
+
+test('preserves iife wrapper name', async t => {
+  const minifiedBundle = readFileSync(join('test/input/iife-wrapped-minified.js'), 'utf8');
+  const compilerBundle = await rollup({
+    input: 'test/input/iife-wrapped.js',
+    plugins: [
+      compiler(),
+    ],
+  });
+
+  const compilerResults = await compilerBundle.generate({
+    format: 'iife',
+    name: 'wrapper',
+    sourcemap: true,
+  });
+
+  t.is(compilerResults.code, minifiedBundle);
+});

test/input/es5.js

@@ -14,8 +14,12 @@
  * limitations under the License.
  */
 
-function greeting(name) {
-  return 'hello ' + name;
+function changeContent(name) {
+  document.body.innerHTML = 'hello ' + name;
 }
 
-console.log(greeting('superuser'));
+export function greeting(name) {
+  changeContent(name || 'you');
+
+  document.body.addEventListener('click', greeting('superuser'), false);
+}

test/input/iife-wrapped-minified.js

@@ -0,0 +1 @@
+'use strict';var wrapper=function(a){a.greeting=function(a){document.body.innerHTML="hello "+a};return a}({});

test/input/iife-wrapped.js

@@ -0,0 +1,19 @@
+/**
+ * Copyright 2018 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export function greeting(name) {
+  document.body.innerHTML = 'hello ' + name;
+}

test/rollup-config-to-flags.js

@@ -36,7 +36,11 @@ test('when rollup configuration specifies format iife with a name, an extern is
   t.not(options.externs, undefined);
 
   const externs = readFileSync(options.externs, 'utf8');
-  t.is(externs, `function Wrapper(){}`);
+  t.is(externs, `
+/**
+ * @fileoverview Externs built via derived configuration from Rollup or input code.
+ * @externs
+ */\nvar Wrapper = function(){};`);
 });
 
 test('when rollup configuration specifies format es, assume_function_wrapper is true', t => {