README.md

Every kind of test of Standard §18 on one small checkout: unit tests with assert, assert_eq, assert_fails; a fixture with set-up and clean-up; mock of an external service with scripted answers and calls; a deterministic simulation (test sim, virtual clock, fault injection, one run per seed).

oxl test                 # unit tests
oxl test --kind sim      # simulation, every seed
oxl test --seed 7        # replay one seed

Source: examples/testing-demo/README.md