Advice for mocking zephyr syscalls

[anbutle]

I am working on some unit testing for my project and have run into some issues when trying to mock syscalls, I was wondering if anyone has any advice on a good approach for such a scenario. I am able to successfully mock calls to external libs, and mock out other parts of my application, but am having problems mocking zephyr calls.

In my situation I have the main app project which include the source files I would like to unit test (libapp.a). Within that, I have a file which makes use of the syscall device_get_binding. I target this file in my unit test and try to declare a mock for device_get_binding (Have tried different methods, but currently using fff.h). The issue is that I just get linker errors due to duplicate definitions of device_get_binding.

I guess the root of my issue is that I don't see how I can avoid linking in the actual zephyr syscall impls instead of the mocked version in my test project. Any advice would be appreciated.

[henrikbrixandersen]

Have you considered stubbing out the driver instead? We have several in-tree simulators (see e.g. https://github.com/zephyrproject-rtos/zephyr/blob/master/drivers/flash/flash_simulator.c) for this exact purpose.