KUnit is a unit testing framework decided for the Linux kernel. On April 4, 2019 the first series (after 4 RFC series were submitted) was published to the Linux kernel mailing list.
The framework is documented in Documentation/kunit. It
includes a framwork written in C and a Python wrapper that reads a
defconfig file named kunitconfig. The
wrapper somehow parses that file to build a .config, which
is used to build a user-mode kernel, which is then run as
./linux. The wrapper parses the relevant output and prints
the results.
Unfortunately, I ran into several issues related to the wrapper. The
first was that it did not handle the exit status of
./linux. When running the wrapper with
--raw_output or simply running ./linux several
stack traces were printed including a kernel panic. Also, I could not
get it to select the dependencies defined in the Kconfig file I created
for my tests. It failed while trying to write a config, update it based
on the current kernel and then validate that process.
The only somewhat reasonable solution I could come up with to use kunit to test out-of-tree kernel modules was to setup the kernel module project with the same hierarchy as the kernel and use overlayfs to build it in-tree (see The Overlay Filesystem).