Investigate running CI tests in containers.

[Rosalita]

For ably-go, we had a test which passed in CI but failed when running locally (https://github.com/ably/ably-go/issues/445). The fix for this was to increase the tolerance of a timed assertion by 1ms. One way this kind of issue could be avoided would be to use a tool like Docker to run tests inside a container.

Advantages of containerisation

• If tests were able to run inside a container, the command that runs them would use the same image locally as inside CI. This would eliminate any 'false positive' test failures which were a direct cause of the environment the tests were running in.
• The environment the tests run in would be identical for every test run, making it easier to diagnose the cause of test failures.

Trade offs to consider

• For security, a Docker Image would need to be created and maintained by Ably.
• Every time a new version of Go was released, the image would need to be updated so that the latest version was installed inside the container.

This ticket has been created as a starting point to discuss running CI tests in containers as potentially this could be advantageous to some of our SDKs where we have faced issues with the test environment causing test failures.

┆Issue is synchronized with this Jira Task by Unito