Tempest Field Guide to Scenario tests

What are these tests?

Scenario tests are “through path” tests of OpenStack function. Complicated setups where one part might depend on the completion of a previous part. They ideally involve the integration between multiple OpenStack services to exercise the touch points between them.

Any scenario test should have a real-life use case. An example would be:

  • “As an operator, I want to start with a blank environment”:

    1. upload a glance image

    2. deploy a vm from it

    3. ssh to the guest

    4. create a snapshot of the vm

Why are these tests in Tempest?

This is one of Tempest’s core purposes, testing the integration between projects.

Scope of these tests

Scenario tests should always use the Tempest implementation of the OpenStack API, as we want to ensure that bugs aren’t hidden by the official clients.

Tests should be tagged with which services they exercise, as determined by which client libraries are used directly by the test.

Example of a good test

While we are looking for interaction of 2 or more services, be specific in your interactions. A giant “this is my data center” smoke test is hard to debug when it goes wrong.

A flow of interactions between Glance and Nova, like in the introduction, is a good example. Especially if it involves a repeated interaction when a resource is setup, modified, detached, and then reused later again.