286bf900b1 Address mutants in units (Shing Him Ng)
Pull request description:
Preemptively addressing these mutants before introducing the `cargo-mutants` workflow. There are several types of changes:
- Changes that address mutants that were actually missing
- Changes that address test values that cause `cargo-mutants` to think mutants were missed. For example, `cargo-mutants` will replace the return values for unsigned integer types with 0 and 1. While this case might be tested, the test might be testing this with a call that results in 0 or 1. When `cargo-mutants` substitutes the function call with `Ok(1)`, the test will still pass, and it will consider this a mutant. `cargo-mutants` also replaces operations (+, -, /, %), bitwise operations (&, |, ^, etc), so an operation such as `3 - 2` results in a mutant because changing it to `3 / 2` yields the same result
- TODOs to ignore functions/impls in the future
I uased the following `mutants.toml` config file when running `cargo mutants` and skipped the `Debug`, `Arbitrary`, `Display`, and `Error` impls and the `kani` test:
```
additional_cargo_args = ["--all-features"]
examine_globs = ["units/src/**/*.rs"]
exclude_globs = ["units/src/amount/verification.rs"]
exclude_re = ["impl Debug", "impl Arbitrary", "impl Display", ".*Error", "<impl Visitor for VisitOptAmt<X>>"]
```
I wasn't sure the code for Displaying things needed to be tested with `cargo mutants`, but I'm less sure about the errors so i can kill those mutants too if needed
ACKs for top commit:
tcharding:
ACK 286bf900b1
apoelstra:
ACK 286bf900b1c100d2f5d0a0d45f31a5bf5a0a26ce; successfully ran local tests
Tree-SHA512: 3db9598a5ad92f2013d43876221ce9363cc019cbf720a206768b517a812c8355b7f00594212eb0526c0feb2dc578f88e1df12548f72a2b2360c4d4227de749f7
681de7aa17