View source for TestEngineering/Web/Automation/Flake8 Pre Commit Hook

= Introduction =
The [[QA/Execution/Web_Testing/Docs/Automation/StyleGuide|style guide]] specifies that all Python code adheres to [http://www.python.org/dev/peps/pep-0008/ PEP8]. To prevent committing code that does not pass PEP8, follow these steps to installing a pre-commit to run staged files using the [https://pypi.python.org/pypi/flake8 flake8 checker]. For further assistance on this pre-commit hook please refer the the [http://flake8.readthedocs.org/en/2.3.0/vcs.html 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.