Python package installation from source

python-package-installation-from-source

Summary

Install a Python package directly from its source repository in development mode, with optional dev dependencies, to enable local testing and modification. This skill is essential for validating that a package builds correctly, its test suite passes, and the codebase is functional before contributing or deploying.

When to use

When you need to verify a Python package installs successfully from a cloned or local repository, validate that all tests pass after installation, or prepare a development environment for contributing to the package. Use this when the package is not yet published to PyPI, you need bleeding-edge changes, or you must confirm the CI/CD test workflow works locally.

When NOT to use

• Package is already installed from PyPI and you only need to run it (not develop or modify it).
• Repository has no tests or a broken test suite with known failures unrelated to your changes.
• You are in a read-only environment or production deployment (use stable PyPI releases instead).

Inputs

• Python package source repository (git clone or local directory)
• pyproject.toml or setup.py with dev dependencies defined
• tests/ directory containing pytest test suite

Outputs

• Installed Python package in editable/development mode
• pytest test report (pass/fail for all tests)
• confirmation that package is importable and functional

How to apply

Clone or navigate to the package repository root directory. Install the package in development (editable) mode using pip install -e .[dev] to load source code directly and include development dependencies (typically pytest, code formatters like black, and linting tools). After installation, run the full test suite using pytest tests/ to verify all unit tests pass. Check for a GitHub Actions CI workflow badge or CI configuration (e.g., test-biosynfoni.yml) to confirm the expected test targets. Development installation allows you to modify source code and immediately test changes without reinstalling; success is confirmed when all pytest tests pass without errors.

Related tools

• pip (Package manager used to install the package in editable mode with optional dev dependencies via pip install -e .[dev])
• pytest (Test runner used to execute the complete test suite on the tests/ directory via pytest tests/)
• black (Code formatter recommended for formatting source code before committing changes (invoked pre-submission, optional during dev installation)) — https://github.com/psf/black
• biosynfoni (Example package demonstrating the skill; provides CI workflow reference and dev dependency structure) — https://github.com/lucinamay/biosynfoni

Examples

pip install -e .[dev] && pytest tests/

Evaluation signals

• pip install exits with status 0 and package appears in site-packages or .eggs (confirm with pip show <package> or python -c 'import <package>').
• pytest runs without import errors and discovers all tests in tests/ directory.
• All tests pass with 0 failures, 0 errors (pytest output shows '... passed' with no red X marks).
• Package is importable immediately after install: python -c 'from biosynfoni import Biosynfoni' succeeds.
• GitHub Actions CI workflow badge (e.g., Tests badge in README) shows passing status, confirming same test suite passes in CI.

Limitations

• Development installation requires write access to the repository directory and may conflict with system-wide Python packages if virtual environments are not used.
• No changelog or version history was found in the biosynfoni repository, making it difficult to track which commits or tags correspond to tested versions.
• Platform-specific dependencies (e.g., RDKit compiled binaries) may fail on certain OS/architecture combinations despite successful local installation elsewhere.
• Dev dependencies must be explicitly defined in pyproject.toml or setup.py; if missing or incomplete, tests may fail due to unmet imports.

Evidence

• [other] Install the package in development mode using pip with dev dependencies via pip install -e .[dev].: "Install the package in development mode using pip with dev dependencies via pip install -e .[dev]."
• [other] Execute the complete test suite using pytest on the tests/ directory with pytest tests/.: "Execute the complete test suite using pytest on the tests/ directory with pytest tests/."
• [other] The biosynfoni package has a GitHub Actions CI workflow that runs tests, as indicated by the Tests badge displayed in the repository.: "The biosynfoni package has a GitHub Actions CI workflow that runs tests, as indicated by the Tests badge displayed in the repository."
• [other] Run the following command from the root of the project to install the project for development: "Run the following command from the root of the project to install the project for development"
• [other] You can also run the tests locally with the following command: "You can also run the tests locally with the following command"
• [readme] Biosynfoni requires Python 3.9 or later. RDKit is installed as a dependency when installing Biosynfoni.: "Biosynfoni requires Python 3.9 or later. RDKit is installed as a dependency when installing Biosynfoni."