test_00_signup_api.py

def test_sign_up_01(client):
    # Sign up a user by testing the ``POST /signup/`` API endpoint.
    response = client.post(
        "/signup/",
        json={"username": "username", "password": "password"},
    )
    assert response.status_code == 200
    assert response.json == {"message": "Registration successful"}

    # If you want to go an extra step, can also check if the entry was created
    # in the database or not. But, that is optional as you can verify the same
    # in the signin API test.