default or selected kernelversion does not have config value CONFIG_TEST_CPUMASK.
Result is shown for kernelversion 6.1-rc2

cpumask tests

modulename: test_cpumask.ko


Linux Kernel Configuration
└─>Kernel hacking
└─>Kernel Testing and Coverage
└─>Runtime Testing
└─>KUnit - Enable support for unit tests
└─>cpumask tests
In linux kernel since version 6.0.1 (release Date: 2022-10-12)  
Enable to turn on cpumask tests, running at boot or module load time.

If unsure, say N.

source code: