Add unittest

Add unittest

[   24s] + ./char
[   24s]
[   24s] running 1 test
[   24s] test test_char ... ok
[   24s]
[   24s] test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.01s
[   24s]
[   24s] + for unit_test in '${unit_test_list}'
[   24s] + ./smoke
[   24s]
[   24s] running 10 tests
[   24s] test bool ... ok
[   24s] test fill ... ok
[   24s] test i8 ... ok
[   24s] test rng ... ok
[   24s] test rng_init ... ok
[   24s] test u8 ... ok
[   24s] test with_seed ... ok
[   24s] test u32 ... ok
[   25s] test u64 ... ok
[   25s] test u128 ... ok
[   25s]
[   25s] test result: ok. 10 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 1.45s