how to run pytest ?

Run from the directory clients\python, as python -m pytest: python -m puts that directory first on sys.path, so the tests exercise the package in this repository even when a released ideastatica-connection-api is installed. A bare pytest resolves the import to whatever is installed instead, which is the way to test an installed wheel.

# Step 1: Create a virtual environment
python -m venv venv

# Step 2: Activate the virtual environment
.\venv\Scripts\activate  # On Windows

# Step 3: Install dependencies
pip install -r requirements.txt -r test-requirements.txt

# Step 4: Run the offline unit tests - what CI runs on every pull request
python -m pytest -m "not requires_service"

# Step 5: Run everything, with a Connection REST API service listening on http://localhost:5000
python -m pytest

A test that needs the running service goes into a module marked pytestmark = pytest.mark.requires_service (the marker is registered in tox.ini); otherwise CI runs it without a service and it fails.