OSS + ELC EU 2026

In Zephyr, subsystems, middleware, and application components typically depend on one or more lower-level device driver APIs. For testing these upper-level subsystems in isolation, the lower-level driver dependencies must still be satisfied. A popular software design pattern for this is to use test doubles. However, how can this be achieved in Zephyr without introducing test-specific changes to the upper-level subsystem?

The solution is to use fake drivers. This presentation will explore various use cases for employing fake device drivers as test doubles, examine the structure of a fake driver implementation, and demonstrate how fake drivers can be used to not only satisfy test dependencies, but also facilitate test case isolation, driver API call inspection and instrumentation.