[IO-1334][internal] E2E Testing config

[owencjones]

Problem

E2E Tests had no config solution

Solution

Added a conftest.py file that incoporated environment variables, with optional dotenv for use on local machines. Also added a fixture that is global, and session bound (runs once per test session, not once per test) that allows for these values to be included in tests easily. Have also added custom E2E exceptions that the config code can raise so that if our system raises an error we foresee in config, we can easily spot these in CI.

NB: Have deliberately not included the staging URL in the defaults, as it would go into our public code if I did, and possibly shouldn't.

Changelog

e2e_tests/conftest.py
e2e_tests/exceptions.py
e2e_tests/pytest.ini
e2e_tests/test_example.py

• Added test configuration file with hook to accept and parse config, and fixture to share it
• Added custom exceptions for E2E tests
• Added to example test to offer green that this works.

[linear]

IO-1334 Test setup configuration

Setup the new E2E test system to be easily pointed at any server we have, and configure it to point at staging.darwin.com for now.