Float To Top errors when file only has newlines

[johnpaulett]

I had a blank __init__.py with a newline in it, with float_to_top = true in my .isort.cfg after upgrading from 4.x.

The __init__.py should not have the newline, but I had removed a few imports and left the newline in the file. Unfortunately, the isort error made tracking down which file was causing the issue difficult, since I was running isort . on a large project.

Encountered with 0.5.2, 0.5.4, & 0.5.5.

A minimal example:

$ echo "\n" > example.py
$ .venv/bin/isort --float-to-top example.py
Traceback (most recent call last):
  File ".venv/bin/isort", line 10, in <module>
    sys.exit(main())
  File ".venv/lib/python3.8/site-packages/isort/main.py", line 876, in main
    for sort_attempt in attempt_iterator:
  File ".venv/lib/python3.8/site-packages/isort/main.py", line 865, in <genexpr>
    sort_imports(  # type: ignore
  File ".venv/lib/python3.8/site-packages/isort/main.py", line 93, in sort_imports
    incorrectly_sorted = not api.sort_file(
  File ".venv/lib/python3.8/site-packages/isort/api.py", line 321, in sort_file
    changed = sort_stream(
  File ".venv/lib/python3.8/site-packages/isort/api.py", line 158, in sort_stream
    changed = core.process(
  File ".venv/lib/python3.8/site-packages/isort/core.py", line 89, in process
    while current[-1] == "\n":
IndexError: string index out of range

Removing the blank line in example.py resolves the issue. Also not an issue with --float-to-top not used.

Ideally this file would not cause any issue when --float-to-top is used. It may also be nice if an indication is given as to what file is being processed when internal errors occur, to allow manual review of that file for Python syntax errors.

[johnpaulett]

Wonderful! Thanks @timothycrosley

[timothycrosley]

No problem happy I could help! Just released it to PyPI as 5.5.1