Test Driven Development for Embedded C

When to Use a Test Double

Not all interactions will use test doubles. My rule of thumb is to use the real code when you can and use a test double when you must. You will need to use judgment to decide when to fake and when not to fake.

For example, if the CUT uses a linked list as one of its collaborators, there is no need to use a fake linked list. Use the real one. The test case consults the linked list during the verify stage of the Four-Phase Test pattern to see whether the right additions, deletions, and modifications were made to the linked list.

Here are some common reasons to use a test double:

Hardware independence

Having test doubles for hardware interactions will allow testing independently from the hardware. It also provides ...