I actually was wrong about this:

Supported modes on windows are 0444 and 0666.

Picking 0666 is not great for a test because that's the default mode for new files on windows. 0444 would be a better choice.

Note that on windows it isn't possible to delete files that are read-only. So you probably want to make them writable before attempting to unlink them. e.g.

```js
if (isWindows)
  fs.chmodSync(file1, 0666)
```