I noticed that the default mode is w, which in tempfile.NamedTempFile() always converts line endings based on the os.linesep. If I have a data with \n line endings, atom_write() by default converts it to \r\n on Windows. And vice-versa on Linux.

Python 3's open() introduced a new option, newlines to improve control over how line endings are handled. It's available in both Python 3 and Python 2 via io.open().

• https://docs.python.org/3/library/functions.html#open

I can work around the problem by specifying the mode as w+b, but then on Python 3 I also have to make sure the string is encoded as bytes. It would be convenient if this library used io.open and propagated the newline parameter. Setting newline='' then does not perform any translation on line endings.