misterbrownlee / fsx-copy-test

Where I test a thing that is wonky in fs-extra

fsx-copy-test

Where I test a thing that is wonky in fs-extra

why

A weird behavior or mild contraction in the fs-extra docs for copy.

The user case is is having two directories, with distinct subdirectories, and wanting copy to merge them when copying into a single directorty with the correct subdirectories. Makes sense? Like this:

source
  |
  o-- foo
  |    |
  |    o-- fooFiles
  |           ... many foo files ...
  |       
  |
  o-- bar
  |    |
  |    o-- barFiles
  |           ... many bar files ...
  |       

I would expect this to work:

const tasks = [
  fsx.copy('source/foo/', 'output/'),
  fsx.copy('source/bar/', 'output/')
]

Promise.all(tasks)
  .then(()=> {
    console.log('Winner winner chicken dinner');
  });

With this result:

output
  |
  o-- fooFiles
  |     ... many foo files ...
  |       
  |
  o-- barFiles
  |     ... many bar files ...
  | 

What happens? When starting the second attempt to copy, even though the first copy has created the needed parent folders, the second will crash with Error: EEXIST: file already exists. There technically isn't a need to overwrite in the traditonal sense (it's just re-using the existing parent directory structure), and the docs say overwrite defaults to true anyway. Regardless, it crashes.

FAKE OVERWRITE. SAD.

The workaround is to call .ensureDir(pathToCopy) when running concurrent copy directory tasks, which makes it behave as expected. The code for that isn't terribly cumbersom:

  const dest = path.resolve('output');
  const fooSrc = path.resolve('source', 'foo');
  const fooDest = path.join(dest, path.parse(fooSrc).base);
  fsx.ensureDir(fooDest).then(fsx.copy(fooSrc, dest));

Solution

I guess just documenting the workaround, for starters. I sent a pull request for that. Better might be to have it work as expected without having to send an option that is supposedly the default? I won't have time to look into that right now, but maybe someday...

Thanks, btw, for the great library. I use it a lot.

Best - Aaron