brew/.github/copilot-instructions.md

Copilot Instructions for Homebrew/brew

This is a Ruby based repository with Bash scripts for faster execution. It is primarily responsible for providing the brew command for the Homebrew package manager. Please follow these guidelines when contributing:

Code Standards

Required Before Each Commit

• Run brew typecheck to verify types are declared correctly using Sorbet.
• Run brew style --fix to lint code formatting using RuboCop. Individual files can be checked/fixed by passing them as arguments.
• Run brew tests --online to ensure that RSpec unit tests are passing (although some online tests may be flaky so can be ignored if they pass on a rerun). Individual test files can be passed with --only e.g. to test Library/Homebrew/cmd/reinstall.rb with Library/Homebrew/test/cmd/reinstall_spec.rb run brew tests --only=cmd/reinstall.

Development Flow

• Write new code (using Sorbet sig type signatures and typed: strict files whenever possible, but not for test files)
• Write new tests (avoid more than one :integration_test per file for speed)

Repository Structure

• bin/brew: Homebrew's brew command main Bash entry point script
• completions/: Generated shell (bash/fish/zsh) completion files. Don't edit directly, regenerate with brew generate-man-completions
• Library/Homebrew/: Homebrew's core Ruby (with a little bash) logic.
• Library/Homebrew/bundle/: Homebrew's brew bundle command.
• Library/Homebrew/cask/: Homebrew's Cask classes and DSL.
• Library/Homebrew/extend/os/: Homebrew's OS-specific (i.e. macOS or Linux) class extension logic.
• Library/Homebrew/formula.rb: Homebrew's Formula class and DSL.
• docs/: Documentation for Homebrew users, contributors and maintainers. Consult these for best practices and help.
• manpages/: Generated man documentation files. Don't edit directly, regenerate with brew generate-man-completions
• package/: Files to generate the macOS .pkg file.

Key Guidelines

1. Follow Ruby best practices and idiomatic patterns
2. Maintain existing code structure and organisation
3. Write unit tests for new functionality. Use one assertion per test where possible.
4. Document public APIs and complex logic. Suggest changes to the docs/ folder when appropriate