fix(rollup): CommonJS not supported in transforms

[JamieMason]

Description

Using ES Modules is fine, but require calls are behaving unexpectedly.

1. Create a file eg /path/to/transform.js:

   const { a } = require('./a');
   
   export default babel => {
     const { types: t } = babel;
     console.log(a());
     return {
       visitor: {
         Program(path) {
           path.traverse({
             enter(path) {
               t.removeComments(path.node);
             }
           });
         }
       }
     };
   };

2. Create a file eg /path/to/a.js:

   module.exports = {
     a: () => 'AAAA'
   };

3. Select babelv7 in the Transform Menu

4. Choose /path/to/transform.js

Expected Output

'use strict';

const a = () => 'AAAA';

var main = babel => {
  const { types: t } = babel;
  console.log(a());
  return {
    visitor: {
      Program(path) {
        path.traverse({
          enter(path) {
            t.removeComments(path.node);
          }
        });
      }
    }
  };
};

module.exports = main;

Actual Output

Cannot find module './a'

rollup.js REPL Examples

1. This ES Modules example is fine.

2. This CommonJS example doesn't error like it does in Electron (Electron could be a factor) but it also doesn't bundle in the contents of /path/to/a.js – it leaves the require calls there.

Suggested Solution

https://github.com/rollup/rollup-plugin-node-resolve and/or https://github.com/rollup/rollup-plugin-commonj might possibly be needed.

Help Needed

Ideas welcome, I'm stuck so far after an hour or two working on this.