@codacy/tools-pylint-4

Table of Contents

• Overview
• Updating patterns
• Updating the Pylint version
• Development
• Notes for maintainers

Overview

Python static analyzer using the Pylint binary. Uses the CLI execution strategy — installs pylint into a dedicated venv, spawns it via spawnTool(), and parses its JSON2 output.

Updating patterns

# Re-fetch pattern metadata from the Codacy API
pnpm prefetch

# Commit the result
git add src/patterns.json

Pattern IDs follow the format PyLintPython3_C0114, PyLintPython3_E0602, etc.

Updating the Pylint version

1. Update PREFERRED_VERSION and the pylint==X.Y.Z entry in PIP_PACKAGES in src/adapter.ts
2. Run pnpm prefetch to check for new/removed rules
3. Run pnpm test to verify compatibility
4. If the major version changes, create a new adapter package (pylint-4/)

Development

pnpm build    # Build with tsup
pnpm test     # Run tests (requires pylint in PATH or auto-installed)

Install pylint manually for local development:

pip install pylint

Or let the adapter auto-install into a venv:

codacy-analysis analyze . --install-dependencies

The adapter installs these packages into the venv:

• pylint==4.0.8
• pylint-django
• pylint-flask
• pylint-celery
• pylint-common
• pylint-beam
• pylint-pytest
• SaltPyLint

Notes for maintainers

• JSON2 output format: The adapter uses --output-format=json2 which outputs { "messages": [...], "statistics": {...} }. This is the modern format (Pylint 3.x+).
• 0-based columns: Pylint reports columns as 0-based. The adapter adds 1 to convert to the 1-based model used by Codacy.
• Nullable endLine/endColumn: These fields can be null in Pylint output. The adapter omits them from Issue objects when null.
• Exit code bitmask: Pylint uses a bitmask exit code. Bit 5 (value 32) indicates a usage error (bad config/args). Bits 0-4 (values 1-31) indicate normal findings. The adapter checks exitCode & 32 to distinguish errors from normal findings.
• E0401 filtering: The E0401 (import-error) pattern is permanently filtered because sandboxed environments cannot resolve third-party imports. This matches the existing Codacy wrapper behavior.
• Plugin support: The adapter bundles the same plugins as the Codacy wrapper (pylint-django, pylint-flask, pylint-celery, pylint-common, pylint-beam, pylint-pytest, SaltPyLint).
• Pattern parameters: Some patterns accept parameters (e.g. max-line-length for C0301, max-locals for R0914). These are passed as --{param}={value} CLI arguments.
• Python 3.10+: pylint 4 dropped 3.9, so install passes >=3.10.0 to ensurePython (an older system Python, e.g. Apple's 3.9 /usr/bin/python3, is skipped and a portable 3.12 is downloaded) and to ensureVenv (a venv an earlier install built on 3.9 is rebuilt, not reused).
• Venv isolation: Pylint and its plugins are installed in a dedicated venv at ~/.codacy/runtimes/PyLintPython3/venv/ to avoid dependency conflicts with other Python tools. The path is keyed on the stable tool ID rather than the package folder name, so a major bump keeps the venv and upgrades it in place instead of orphaning it.
• Config files: The adapter reports pylintrc or .pylintrc (in that order) as a local configuration file, and nothing else. Codacy Cloud accepts only those two names, so pyproject.toml, setup.cfg, tox.ini and pylintrc.toml never count, even with a Pylint section. Pylint still reads them at run time for its other settings.