Set up Python test environment in Claude Code for web where flox is unavailable. Use when you need to run backend tests and `uv sync` fails due to Python version mismatch.
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.
The project requires a specific Python version pinned in pyproject.toml (check requires-python), but:
uv python install <version> may fail if the version isn't yet indexed by uvuv sync enforces the exact version constraint and will fail with the wrong Python versionDownload 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.
cd /home/user/posthog
uv sync --python /tmp/python-install/python/bin/python3
source .venv/bin/activate
# Run a specific test (if hogli is available)
hogli test path/to/test.py::TestClass::test_method -v
# Or use pytest directly
pytest path/to/test.py::TestClass::test_method -v
# Run all tests in a directory
hogli test posthog/hogql/test/ -v
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.
Tests expect certain hostnames to resolve to localhost:
echo "127.0.0.1 kafka clickhouse clickhouse-coordinator objectstorage" | sudo tee -a /etc/hosts
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.
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
For SAML-related functionality:
sudo apt-get update
sudo apt-get install libxml2-dev libxmlsec1-dev libxmlsec1-openssl
The pytest.ini sets:
pythonpath = . commonDJANGO_SETTINGS_MODULE = posthog.settingsDEBUG=1, TEST=1Default ignores: --ignore=posthog/user_scripts --ignore=services/llm-gateway --ignore=common/ingestion/acceptance_tests
If you encounter issues with the test setup, refer to .github/workflows/ci-backend.yml for the authoritative CI configuration. This file shows: