The default tests test all parts.
However, it is possible to extend the testsuite by pointing the binary to the test directory of the JSON-Schema.org testsuite.
You can obtain these by cloning the official testsuite:
https://github.com/json-schema-org/JSON-Schema-Test-Suite
git clone https://github.com/json-schema-org/JSON-Schema-Test-Suite.git
and then run the testsuite with the --test-dir argument:
./testschema --testdir=JSON-Schema-Test-Suite/tests/draft2020-12