Committing to Excellence - How Pre-Commit hooks keep my codebase prettier

10 September 2023 - 4 mins read time
Tags: Software Development Clean Code Python

Pre-commit hooks in Git are like your code’s personal stylist, working their magic just before it hits the stage (the repository). They’re the backstage crew making sure your commits look sharp, sound good, and bring their A-game. These hooks let you run scripts and commands to ensure your code meets the highest quality standards. It’s like having a mini-festival in your local environment, with tasks that include code formatting for the perfect outfit, linting to catch style blunders, and even testing to make sure your code is ready to rock the show without any surprises!

To set up pre-commit from scratch, you can follow these steps:

Create a new project directory for your code, and navigate to it using the command line. The .pre-commit-config.yaml file is also located in the root directory, and contains the configuration for the pre-commit hooks that will be run on the code before committing changes to the repository.
Create a virtual environment using python by running the following command python3 -m venv .venv where .venv is the name of oyurt virtual environment.
Activate it by running the command source .venv/bin/activate
Install pre-commit using pip by running pip install pre-commit.
Install pytest using pip by running pip install pytest.
Initialize pre-commit in your project directory by running pre-commit init.
Create a .pre-commit-config.yaml file in your project directory with the hooks you want to run. This pre-commit configuration specifies a set of hooks to be executed before committing changes to the repository. A sample .yaml is shown below.

repos:
-   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v2.3.0
    hooks:
    -   id: check-yaml
    -   id: end-of-file-fixer
    -   id: trailing-whitespace
    -   id: check-docstring-first
    -   id: check-merge-conflict
    -   id: mixed-line-ending
        args: [--fix=lf]

-   repo: https://github.com/PyCQA/isort
    rev: 5.12.0
    hooks:
    -   id: isort
        args: ["--profile", "black", "--filter-files"]
-   repo: https://github.com/psf/black
    rev: 23.9.1
    hooks:
    -   id: black
- repo: https://github.com/pycqa/flake8
    rev: 4.0.1
    hooks:
    -   id: flake8
# optional (if you have any test scripts)
-   repo: local
    hooks:
  -     id: run_tests
        language: script
        name: Run tests
        entry: ./run_test.sh
        stage: [commit]

Specifically, it does the following:

Configures the Black formatter and the Black Jupyter extension to format Python code in a standardized way.
Configures the Flake8 linter to check for style violations and errors in the code.
Configures the trailing-whitespace hook to remove any trailing whitespace in the files being committed.
Optional: Configures a custom run_tests hook to run a script that executes the test suite for the project.

“repos” is a keyword in the pre-commit configuration file that specifies a list of Git repositories containing hooks that should be installed and used by the pre-commit framework. Each repository in the list is specified as a YAML dictionary with the following keys:

repo: The URL of the Git repository containing the hooks.
rev: The revision (tag, branch or commit hash) to checkout from the repository.
hooks: A list of hooks to install and use from the repository.

Install the hooks in your virtual environment by running pre-commit install.

After following these steps, pre-commit will run automatically before every commit to ensure that the code conforms to the rules defined by the hooks in the .pre-commit-config.yaml file.

As we wrap up our pre-commit hook adventure, it’s time to embrace the groovier, cleaner, and more polished Git experience they bring. With these magical tools, your code commits will be the rockstars of your repository – perfectly styled, in tune, and ready to hit the stage even if multiple people are working on the same codebase. Say goodbye to last-minute errors and code mishaps by leting the power of pre-commit hooks take your coding journey to a whole new level, where quality and style are non-negotiable! Keep coding, keep committing, and always keep it funky!