Manually test new opcode on LIGO
Formal test is somehow hard to write in OCaml and so I recommend a shell based smoke test.
After compile the custom ligo with custom Tezos, then run
ligo compile-expression "$(cat src/test/contracts/level_lock.ligo)" -s pascaligo
and you'll see your opcode is generated from ligo compiler.
It's good to use
as a stable compiler