How to Measure Code Coverage in Rust

Rust does not include a built-in code coverage tool, so you must install the cargo-tarpaulin crate to measure it. Run the following command to install the tool and then execute your tests with coverage reporting enabled:

cargo install cargo-tarpaulin
cargo tarpaulin --out Html

This generates an HTML report in the tarpaulin-report.html file showing which lines of your code were executed during the test run.

Code coverage measures how much of your code is actually tested when you run your test suite. It helps you find parts of your program that might have bugs because no test touches them. Think of it like a map that highlights the roads you've driven on, showing you exactly which paths you haven't explored yet.