Claude Code for web — test setup

This document describes how to set up and run Python tests in a Claude Code for web environment, where flox is not available.

If you get stuck following these instructions, please bail out to the user and seek their guidance. Please suggest that they update this guide.

Problem

The project requires a specific Python version pinned in pyproject.toml (check requires-python), but:

• Claude Code for web environments may have a different system Python version
• uv python install <version> may fail if the version isn’t yet indexed by uv
• uv sync enforces the exact version constraint and will fail with the wrong Python version

Solution: Download Python from python-build-standalone

Download the exact version from python-build-standalone GitHub releases. The script below auto-detects the required version from pyproject.toml:

# Auto-detect the required version from pyproject.toml
REQUIRED_VERSION=$(grep requires-python pyproject.toml | grep -oP '[\d.]+')
echo "Required Python: $REQUIRED_VERSION"

# Get the latest release tag from python-build-standalone
RELEASE_TAG=$(curl -sL "https://api.github.com/repos/astral-sh/python-build-standalone/releases/latest" | grep '"tag_name"' | cut -d'"' -f4)

# Find and download the matching build
DOWNLOAD_URL=$(curl -sL "https://api.github.com/repos/astral-sh/python-build-standalone/releases/latest" | \
  grep "browser_download_url" | grep "$REQUIRED_VERSION" | grep "x86_64-unknown-linux-gnu-install_only.tar.gz" | head -1 | cut -d'"' -f4)

mkdir -p /tmp/python-install && cd /tmp/python-install
curl -L -o python.tar.gz "$DOWNLOAD_URL"
tar -xzf python.tar.gz

# Verify
/tmp/python-install/python/bin/python3 --version

If the auto-detection doesn’t find a URL (e.g., the version is too new), browse the releases page manually and look for a cpython-<version>+<tag>-x86_64-unknown-linux-gnu-install_only.tar.gz asset.

Install dependencies and run tests

cd /home/user/posthog
uv sync --python /tmp/python-install/python/bin/python3
source .venv/bin/activate

# Run a specific test
pytest path/to/test.py::TestClass::test_method -v

# Run all tests in a directory
pytest posthog/hogql/test/ -v

Docker Services

Most tests require backend services running. If Docker is available, start them with:

docker compose -f docker-compose.dev.yml up -d

See docker-compose.dev.yml for the full list of services and ports. Some test directories have specific service requirements documented in their own configuration files.

Hosts file setup

Tests expect certain hostnames to resolve to localhost:

echo "127.0.0.1 kafka clickhouse clickhouse-coordinator objectstorage" | sudo tee -a /etc/hosts

Environment Variables

Tests require environment variables defined in .github/workflows/ci-backend.yml (see the env: section at the top of the file). You can also copy .env.example to .env for local development defaults.

Additional Setup

Frontend dist placeholders

Some tests require frontend build artifacts to exist (even if empty):

mkdir -p frontend/dist
touch frontend/dist/index.html
touch frontend/dist/layout.html
touch frontend/dist/exporter.html

SAML dependencies (if needed)

For SAML-related functionality:

sudo apt-get update
sudo apt-get install libxml2-dev libxmlsec1-dev libxmlsec1-openssl

Pytest Configuration

The pytest.ini sets:

• pythonpath = . common
• DJANGO_SETTINGS_MODULE = posthog.settings
• DEBUG=1, TEST=1

Default ignores: --ignore=posthog/user_scripts --ignore=services/llm-gateway --ignore=common/ingestion/acceptance_tests

Debugging Installation Issues

If you encounter issues with the test setup, refer to .github/workflows/ci-backend.yml for the authoritative CI configuration. This file shows:

• Exact Python version used in CI
• System dependencies installed
• Environment variables set
• Docker services configuration
• Test execution commands

Limitations

• Docker unavailable: Tests requiring services will fail without Docker
• Network restrictions: Downloading Python requires GitHub access
• Temporal tests: Require additional Temporal service setup