Code test coverage?

[m1212e]

Did you consider or event already use some kind of code coverage tool? I can recommend tarpaulin.

[fundon]

Yes, need it, and need to add more test cases. cargo-llvm-cov is also good.
tarpaulin has not been maintained for too long.

[fundon]

$ cargo llvm-cov --html -- --nocapture
$ open target/llvm-cov/html/index.html