Creating Custom Credo Checks for Elixir Projects

The article by Paweł Świątkowski is a detailed tutorial on how to write custom checks for Credo, a static code analysis tool for the Elixir language. It starts with a motivation for creating custom checks, such as enforcing coding conventions or preventing certain patterns in the codebase. The guide then proceeds to the basics of setting up Credo in an Elixir project, followed by an explanation of Credo checks' anatomy, including their categories, priority, name, and execution mechanism. Świątkowski provides a practical example where a custom check is developed to prevent 'bare imports' in an Elixir module, demonstrating the process of matching patterns using the abstract syntax tree (AST), testing the check, and registering it with Credo. The article finishes with tips on improving the check's explanation and its display when running the `mix credo explain` command. It's a comprehensive guide aimed at Elixir developers interested in maintaining high code quality through custom static analysis.