GDriveFileSystem: Raise FIleNotFoundError on ls.

[daavoo]

Per iterative/dvc-gdrive#29

[skshetry]

Turns out, fs.mkdir() is not implemented in GDriveFileSystem. I was not sure if it was needed as it has been working fine for so long. So I only fixed in test to create a directory.

[skshetry]

Investigating some failures in iterative/dvc-gdrive#28. Will merge this after they turn green.

[skshetry]

Looks like find() is also not working correctly. Will look into it next week.

[daavoo]

Looks like find() is also not working correctly. Will look into it next week.

What is the failure or case where is not working?

[skshetry]

Looks like find() is also not working correctly. Will look into it next week.

What is the failure or case where is not working?

See iterative/dvc-gdrive#28. The following returns an empty list even though the file exists, failing status checks.

>>> fs.find("root/<>/files/md5")
[]

I am still trying to understand internals of GDriveFileSystem on how to fix it.

This piece of code is problematic:

PyDrive2/pydrive2/fs/spec.py

Lines 476 to 482 in a5dc1d9

	while dir_ids:
	query_ids = {
	dir_id: dir_name
	for dir_id, dir_name in dir_ids.pop().items()
	if posixpath.commonpath([base, dir_name]) == base
	if dir_id not in seen_paths
	}