Test refactors and coverage (#6)

## Summary

This adds a substantial refactor to our test suite as well as tooling
for coverage and nicer test runner with nextest.

## Type of Change

<!-- Mark with an `x` all that apply -->

- [ ] 🐛 Bug fix (non-breaking change that fixes an issue)
- [ ] ✨ New feature (non-breaking change that adds functionality)
- [ ] 💥 Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] 📚 Documentation update
- [x] 🧹 Code cleanup or refactoring
- [ ] 🔧 Build system or dependency changes
- [x] 🧪 Test improvements

## How Has This Been Tested?

<!-- Describe the tests you ran to verify your changes -->

- [x] Existing tests pass (`mise test`)
- [x] New tests added for new functionality
- [x] Manual testing performed
- [x] Code follows style guidelines (`mise lint`)

Author: aaronmallen

.gitignore

@@ -1,3 +1,4 @@
 /.idea/
+/coverage/
 /target/
 .DS_Store

bin/setup

@@ -1,4 +1,5 @@
 #!/usr/bin/env sh
 #MISE description="install dependencies and setup the dev environment"
 
-cargo install cargo-audit cargo-outdated cargo-sort
+rustup component add --toolchain nightly-x86_64-unknown-linux-gnu clippy
+cargo install cargo-audit cargo-llvm-cov cargo-nextest cargo-outdated cargo-sort

bin/test

@@ -2,4 +2,6 @@
 #MISE description="run unit tests"
 #MISE alias=["t"]
 
-cargo test
+cargo llvm-cov nextest --branch --summary-only
+cargo llvm-cov report --branch --html --output-dir coverage
+cargo llvm-cov report --branch --lcov --output-path coverage/lcov.info

mise.toml

@@ -2,5 +2,10 @@
 includes = ["bin"]
 
 [tools]
+"cargo:cargo-audit" = "latest"
+"cargo:cargo-llvm-cov" = "latest"
+"cargo:cargo-nextest" = "latest"
+"cargo:cargo-outdated" = "latest"
+"cargo:cargo-sort" = "latest"
 "npm:markdownlint-cli" = "latest"
-rust = "1.89"
+rust = { version = "nightly", components = "clippy,llvm-tools-preview,rustfmt,rust-src" }

rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
 channel = "nightly"
-components = ["clippy", "rustfmt"]
+components = ["clippy", "llvm-tools-preview", "rustfmt", "rust-src"]