Tempest is designed to be useful for a large number of different environments. This includes being useful for gating commits to OpenStack core projects, being used to validate OpenStack cloud implementations for both correctness, as well as a burn in tool for OpenStack clouds.
As such Tempest tests come in many flavors, each with its own rules and guidelines. Below is the overview of the Tempest repository structure to make this clear.
tempest/
api/ - API tests
scenario/ - complex scenario tests
serial_tests/ - tests that run always in the serial mode
tests/ - unit tests for Tempest internalsEach of these directories contains different types of tests. What belongs in each directory, the rules and examples for good tests, are documented in a README.rst file in the directory.
API tests are validation tests for the OpenStack API. They should not use the existing Python clients for OpenStack, but should instead use the Tempest implementations of clients. Having raw clients let us pass invalid JSON to the APIs and see the results, something we could not get with the native clients.
When it makes sense, API testing should be moved closer to the projects themselves, possibly as functional tests in their unit test frameworks.
Scenario tests are complex "through path" tests for OpenStack functionality. They are typically a series of steps where a complicated state requiring multiple services is set up exercised, and torn down.
Scenario tests should not use the existing Python clients for OpenStack, but should instead use the Tempest implementations of clients.
Tests within this category will always be executed serially from the rest of the test cases.
Unit tests are the self checks for Tempest. They provide functional verification and regression checking for the internal components of Tempest. They should be used to just verify that the individual pieces of Tempest are working as expected.