This post is part of the Elixir Setup Series, covering essential tools and practices for Elixir projects.

Adding Credo to Your Elixir Project

Credo automates and enforces team-wide standards through linting and code analysis, checking for style consistency, readability, and potential bugs. Integrating Credo into your workflow ensures that your codebase adheres to best practices, making it easier to maintain and reducing the likelihood of introducing errors.

See the code

See the documentation

Add credo to Mix Dependencies

First, add Credo to the list of dependencies in the mix.exs file:

defp deps do
  [
    {:credo, "~> 1.6", only: [:dev, :test], runtime: false}
  ]
end

Limit Credo to the development and test environments, and then update your dependencies:

mix deps.get

Generate a Credo Configuration

To customize Credo’s behavior, generate a .credo.exs configuration file:

mix credo.gen.config

The .credo.exs file can be edited to fit your project’s needs.

Integrating Credo into the Makefile

While you can use the mix file’s aliases, I prefer using a Makefile to manage tasks.

lint:
 @echo "Linting code..."
 MIX_ENV=dev mix credo --strict

Running Credo in --strict mode provides additional feedback.

Check for Lint Errors

To check for lint errors, run:

make lint

This will run Credo locally, ensuring that your code meets style and readability standards.

Add a Git Hook to Run Credo on Push

To automate code analysis when pushing changes to your repository, add a pre-push hook:

  1. Create the Pre-Push Hook Script:

    Create or modify the pre-push file:

    nano .git/hooks/pre-push

  2. Add the Following Script to the pre-push File:

    #!/bin/sh

echo "Running Credo to check for code consistency..."
mix credo --strict

# Capture the exit status of Credo
CREDO_EXIT_CODE=$?

# Check if Credo found any problems
if [ $CREDO_EXIT_CODE -ne 0 ]; then
  echo "Credo found issues."
  echo "Please fix them before pushing!"
  exit 1
fi

echo "No issues found by Credo. Proceeding with push."
exit 0

  3. Make the Pre-Push Script Executable:

    chmod +x .git/hooks/pre-push

Now, whenever you push changes to your repository, Credo will run automatically to check for code consistency and style issues.

Add an Extension to Your Editor

I recommend using the Credo (Elixir Linter) extension for your editor.