tox is a generic virtualenv management and test command line tool

environments, isolated, testing, virtual, formatter, hacktoberfest, tox
pip install tox-ini-fmt==1.3.1



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apply a consistent format to tox.ini files


pip install tox-ini-fmt

as a pre-commit hook

See pre-commit for instructions

Sample .pre-commit-config.yaml:

- repo:
  rev: "1.1.0"
    - id: tox-ini-fmt
      args: ["-p", "fix_lint,type"]


Consult the help for the latest usage:

$ tox-ini-fmt --help
usage: tox-ini-fmt [-h] [-s] [-p toxenv] tox_ini

positional arguments:
  tox_ini       tox ini file to format

optional arguments:
  -h, --help    show this help message and exit
  -s, --stdout  print the formatted text to the stdout (instead of update in-place)
  -p toxenv     tox environments that pin to the start of the envlist (comma separated)

what does it do?

It does not

  • Format any other section beside tox/testenv:* (other than put this sections to the end of the file)


  • boolean fields are normalized to true or false
  • all fields are stripped of white space on both end
  • values that contain a list are split one value per line (PR/merge friendly)
  • indent multi-line values by four spaces, and start on new line
  • substitutions within multi-line (excluding commands) are moved to the start of the list (order kept)

Ordering of sections

Applies the following section order:

  1. tox
  2. testenv
  3. testenv:* - py/pypy envs are ordered in decreasing order by python version, then apply the order defined within envlist part of tox section, you can pin tox elements to the start by using the -p flag
  4. any other section defined within the file

tox section

Order by:

  1. envlist - multi-line, start with py envs in decreasing python order, then same with pypy, then everything else
  2. isolated_build - boolean field
  3. skipsdist - boolean field
  4. skip_missing_interpreters - boolean field
  5. minversion

testenv section

Order by:

  1. description
  2. passenv - multi-line, one environment name to pass per line, sorted by name
  3. setenv - multi-line, one environment name-value to set per line in format of key=value, sorted by key+value
  4. basepython
  5. skip_install - boolean field
  6. usedevelop - boolean field
  7. deps - multi-line, order by package name (but keep dependencies with package names separate at end), normalize format to remove extra spaces
  8. extras - multi-line, one extra env per line
  9. parallel_show_output - boolean field
  10. commands - one command per line, commands that wrap over multiple lines are indented with line two or later by extra four spaces