CONFIG_KGDB_TESTCASE is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin
default or selected kernelversion does not have config value CONFIG_KGDB_TESTCASE.
Result is shown for kernelversion 5.14.15

KGDB: for test case in expect

modulename: kgdb_test.ko

configname: CONFIG_KGDB_TESTCASE

Linux Kernel Configuration
└─>Kernel hacking
└─>KGDB: for test case in expect
In linux kernel since version 2.6.29.1 (release Date: 2009-04-02)  
This is a kgdb test case for automated testing.

source code:
arch/blackfin/kernel/kgdb_test.c