Tempest Library Documentation

Tempest provides a stable library interface that provides external tools or test suites an interface for reusing pieces of Tempest code. Any public interface that lives in tempest/lib in the Tempest repo is treated as a stable public interface and it should be safe to external consume that. Every effort goes into maintaining backwards compatibility with any change. The library is self contained and doesn’t have any dependency on other Tempest internals outside of lib (including no usage of Tempest configuration).


Any code that lives in tempest/lib will be treated as a stable interface. This means that any public interface under the tempest/lib directory is expected to be a stable interface suitable for public consumption. However, for any interfaces outside of tempest/lib in the tempest tree (unless otherwise noted) or any private interfaces the same stability guarantees don’t apply.

Adding Interfaces

When adding an interface to tempest/lib we have to make sure there are no dependencies on any pieces of tempest outside of tempest/lib. This means if for example there is a dependency on the configuration file we need remove that. The other aspect when adding an interface is to make sure it’s really an interface ready for external consumption and something we want to commit to supporting.

Making changes

When making changes to tempest/lib you have to be conscious of the effect of any changes on external consumers. If your proposed change set will change the default behaviour of any interface, or make something which previously worked not after your change, then it is not acceptable. Every effort needs to go into preserving backwards compatibility in changes.


When reviewing a proposed change to tempest/lib code we need to be careful to ensure that we don’t break backward compatibility. For patches that change existing interfaces, we have to be careful to make sure we don’t break any external consumers. Some common red flags are:

  • a change to an existing API requires a change outside the library directory where the interface is being consumed

  • a unit test has to be significantly changed to make the proposed change pass


When adding a new interface to the library we need to at a minimum have unit test coverage. A proposed change to add an interface to tempest/lib that doesn’t have unit tests shouldn’t be accepted. Ideally, these unit tests will provide sufficient coverage to ensure a stable interface moving forward.

Current Library APIs