categories of tests: unit, integration and fuzz. Unit tests can usually be found at
the bottom of a file in a mod block called `tests`. If you add or modify a
function please also add a corresponding test. Integration tests try to test
end-to-end functionality by executing a subcommand of the binary. Those can be
found in the [tests](tests) directory. We don't have a lot of fuzzing but the
basic structure of how we do it can be found in the [fuzz](fuzz) directory.

We strongly recommend installing [just](https://github.com/casey/just) to make
running the tests easier. To run our CI test suite you would do:

```
just ci
```

This corresponds to the commands:

```
cargo fmt -- --check
cargo test --all
cargo test --all -- --ignored
```

Have a look at the [justfile](justfile) to see some more helpful recipes
(commands). Here are a couple more good ones:

```
just fmt
just fuzz
just doc
just watch ltest --all
```

If the tests are failing or hanging, you might need to increase the maximum
number of open files by running `ulimit -n 1024` in your shell before you run