[TODO] Implement integration testing mechanisms

[webknjaz]

• For manual testing, there should be a CLI command accepting JSON payload (string or file), event type and more. (Initial sketch — ✨ Add initial receiver CLI skeleton #14)

• For automated testing, we need fixtures with a similar interface.

• Bonus: it's nice to have a CLI interface for running one-off ad-hoc tasks which may be useful for bulk processing/migrations.

[webknjaz]

This may be helpful: https://github.com/octokit/fixtures-server

[webknjaz]

aiohttp side:

• Add test utils for testing ClientSession aio-libs/aiohttp#1704
• https://github.com/home-assistant/home-assistant/blob/HEAD@%7B2017-04-06T06:51:53Z%7D/tests/test_util/aiohttp.py / https://github.com/home-assistant/home-assistant/blob/dev/tests/test_util/aiohttp.py
• https://github.com/aio-libs/aiohttp/blob/master/examples/fake_server.py
• https://botocore.amazonaws.com/v1/documentation/api/latest/reference/stubber.html
• https://realpython.com/testing-third-party-apis-with-mock-servers/
• https://github.com/pnuckowski/aioresponses
• https://github.com/CircleUp/aresponses

environ-config:

• https://github.com/hynek/environ-config/blob/master/tests/test_environ_config.py
• https://github.com/hynek/environ-config/blob/master/tests/test_secrets.py