Unit Tests for Embedded Code

Stephen Friederichs

Still RelevantIntermediate

I originate from an electrical engineering background and my first industry experience was in a large, staid defense contractor. Both of these experiences contributed to a significant lack of knowledge with regards to software development best...

Summary

This blog explains practical strategies for adding unit tests to embedded firmware, drawing on the author's transition from electrical engineering to software practices. Readers will learn how to isolate hardware dependencies, choose test approaches (host vs target), and integrate tests into the build workflow to improve code quality and catch regressions early.

Key Takeaways

Adopt unit testing early to find logic bugs before hardware brings up complexity
Isolate hardware with mocks, stubs, and a HAL to make fast, repeatable host-based tests
Structure code for testability (small modules, clear interfaces, dependency injection)
Run a mix of host-based and target/HIL tests to balance speed and realism
Integrate unit tests into automated builds/CI to enforce regressions checks

Who Should Read This

Embedded firmware engineers (especially those moving from hardware-focused backgrounds) who want practical, actionable advice on introducing unit tests and improving firmware quality.

Still RelevantIntermediate