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CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

CRITICAL REQUIREMENTS

Test Success

  • ALL tests MUST pass for code to be considered complete and working
  • Never describe code as "working as expected" if there are ANY failing tests
  • Even if specific feature tests pass, failing tests elsewhere indicate broken functionality
  • Changes that break existing tests must be fixed before considering implementation complete
  • A successful implementation must pass linting, type checking, AND all existing tests

Project Overview

libvcs is a lite, typed Python tool for:

  • Detecting and parsing URLs for Git, Mercurial, and Subversion repositories
  • Providing command abstractions for git, hg, and svn
  • Synchronizing repositories locally
  • Creating pytest fixtures for testing with temporary repositories

The library powers vcspull, a tool for managing and synchronizing multiple git, svn, and mercurial repositories.

Development Environment

This project uses:

  • Python 3.9+
  • uv for dependency management
  • ruff for linting and formatting
  • mypy for type checking
  • pytest for testing

Common Commands

Setting Up Environment

# Install dependencies
uv pip install --editable .
uv pip sync

# Install with development dependencies
uv pip install --editable . -G dev

Running Tests

# Run all tests
make test
# or directly with pytest
uv run pytest

# Run a single test file
uv run pytest tests/sync/test_git.py

# Run a specific test
uv run pytest tests/sync/test_git.py::test_remotes

# Run tests with test watcher
make start
# or
uv run ptw .

Linting and Type Checking

# Run ruff for linting
make ruff
# or directly
uv run ruff check .

# Format code with ruff
make ruff_format
# or directly
uv run ruff format .

# Run ruff linting with auto-fixes
uv run ruff check . --fix --show-fixes

# Run mypy for type checking
make mypy
# or directly
uv run mypy src tests

# Watch mode for linting (using entr)
make watch_ruff
make watch_mypy

Development Workflow

Follow this workflow for code changes:

  1. Format First: uv run ruff format .
  2. Run Tests: uv run pytest
  3. Run Linting: uv run ruff check . --fix --show-fixes
  4. Check Types: uv run mypy
  5. Verify Tests Again: uv run pytest

Documentation

# Build documentation
make build_docs

# Start documentation server with auto-reload
make start_docs

# Update documentation CSS/JS
make design_docs

Code Architecture

libvcs is organized into three main modules:

  1. URL Detection and Parsing (libvcs.url)

    • Base URL classes in url/base.py
    • VCS-specific implementations in url/git.py, url/hg.py, and url/svn.py
    • URL registry in url/registry.py
    • Constants in url/constants.py

  2. Command Abstraction (libvcs.cmd)

    • Command classes for git, hg, and svn in cmd/git.py, cmd/hg.py, and cmd/svn.py
    • Built on top of Python's subprocess module (via _internal/subprocess.py)

  3. Repository Synchronization (libvcs.sync)

    • Base sync classes in sync/base.py
    • VCS-specific sync implementations in sync/git.py, sync/hg.py, and sync/svn.py

  4. Internal Utilities (libvcs._internal)

    • Subprocess wrappers in _internal/subprocess.py
    • Data structures in _internal/dataclasses.py and _internal/query_list.py
    • Runtime helpers in _internal/run.py and _internal/shortcuts.py

  5. pytest Plugin (libvcs.pytest_plugin)

    • Provides fixtures for creating temporary repositories for testing

Testing Strategy

libvcs uses pytest for testing with many custom fixtures. The pytest plugin (pytest_plugin.py) defines fixtures for creating temporary repositories for testing. These include:

  • create_git_remote_repo: Creates a git repository for testing
  • create_hg_remote_repo: Creates a Mercurial repository for testing
  • create_svn_remote_repo: Creates a Subversion repository for testing
  • git_repo, svn_repo, hg_repo: Pre-made repository instances
  • set_home, gitconfig, hgconfig, git_commit_envvars: Environment fixtures

These fixtures handle setup and teardown automatically, creating isolated test environments.

For running tests with actual VCS commands, tests will be skipped if the corresponding VCS binary is not installed.

Example Fixture Usage

def test_repo_sync(git_repo):
    # git_repo is already a GitSync instance with a clean repository
    # Use it directly in your tests
    assert git_repo.get_revision() == "initial"

Parameterized Tests

Use typing.NamedTuple for parameterized tests:

class RepoFixture(t.NamedTuple):
    test_id: str  # For test naming
    repo_args: dict[str, t.Any]
    expected_result: str

@pytest.mark.parametrize(
    list(RepoFixture._fields),
    REPO_FIXTURES,
    ids=[test.test_id for test in REPO_FIXTURES],
)
def test_sync(
    # Parameters and fixtures...
):
    # Test implementation

Coding Standards

Imports

  • Use namespace imports for stdlib: import enum instead of from enum import Enum; third-party packages may use from X import Y
  • For typing, use import typing as t and access via namespace: t.NamedTuple, etc.
  • Use from __future__ import annotations at the top of all Python files

Docstrings

Follow NumPy docstring style for all functions and methods:

"""Short description of the function or class.

Detailed description using reStructuredText format.

Parameters
----------
param1 : type
    Description of param1
param2 : type
    Description of param2

Returns
-------
type
    Description of return value
"""

Git Commit Standards

Format commit messages as:

Component/File(commit-type[Subcomponent/method]): Concise description

why: Explanation of necessity or impact.
what:
- Specific technical changes made
- Focused on a single topic

Common commit types:

  • feat: New features or enhancements
  • fix: Bug fixes
  • refactor: Code restructuring without functional change
  • docs: Documentation updates
  • chore: Maintenance (dependencies, tooling, config)
  • test: Test-related updates
  • style: Code style and formatting

Example:

url/git(feat[GitURL]): Add support for custom SSH port syntax

why: Enable parsing of Git URLs with custom SSH ports
what:
- Add port capture to SCP_REGEX pattern
- Update GitURL.to_url() to include port if specified
- Add tests for the new functionality

Debugging Tips

When stuck in debugging loops:

  1. Pause and acknowledge the loop
  2. Minimize to MVP: Remove all debugging cruft and experimental code
  3. Document the issue comprehensively for a fresh approach
  4. Format for portability (using quadruple backticks)