TestEngineering/Web/Automation/Flake8 Pre Commit Hook

Introduction

The style guide specifies that all Python code adheres to PEP8. To prevent committing code that does not pass PEP8, follow these steps to installing a pre-commit to run staged files using the flake8 checker. For further assistance on this pre-commit hook please refer the the official documentation.

Installation

Install flake8 into your global site packages:

    sudo pip install pep8

Change directory to your git repository:

   cd ~/workspace/mygitrepo

Remove any existing pre-commit hooks:

   rm .git/hooks/pre-commit

Install the pre-commit hook:

   flake8 --install-hook

Git Template

You can add this hook to the git template, which means it will be active for all freshly initialised git repositories (unless they already contain a pre-commit hook):

   cd ~/workspace/mygitrepo
   git config --global init.templatedir ~/.git_template
   mkdir ~/.git_template/hooks
   cp .git/hooks/pre-commit ~/.git_template/hooks/

Usage

Once installed, the pre-commit hook will be run whenever you attempt to commit changes to your local repository. Here's an example of it in action:

   git checkout -b TestFlake8
   echo "import os; # comment" > flake8-warnings.py
   git add flake8-warnings.py
   git commit -m 'my commit'
   .../flake8-warnings.py:1:1: F401 'os' imported but unused
   .../flake8-warnings.py:1:10: E703 statement ends with a semicolon
   .../flake8-warnings.py:1:11: E261 at least two spaces before inline comment
   [TestFlake8 ...] my commit
    1 file changed, 1 insertion(+)
    create mode 100644 flake8-warnings.py

Note that by default the warnings are displayed but the commit is still allowed.

Running the Hook

To run the hook directly instead of attempting a commit:

   ./.git/hooks/pre-commit

Preventing Commits

To abort a commit if errors are found:

   export FLAKE8_STRICT=true

You may want to add this to your default profile.

Ignoring Warnings

To ignore certain warnings:

   export FLAKE8_IGNORE=E501

You may want to add this to your default profile.