Build and run tests on 1 job:
cmake -GNinja .. && ninja check
Build on 4 jobs and run tests on 1 job:
cmake -GNinja .. && ninja -j4 check
Build on 4 jobs and run tests on 2 jobs:
cmake -DJCTEST=2 -GNinja .. && ninja -j4 check
Build on 6 jobs and run tests on 2 jobs:
ninja -j6 check