Coverage

User Guide

1. Run coverage with ./tools/coverage.sh.

2. Open this in a web-browser by opening target/debug/coverage/index.html.

3. An lcov file is generated at target/debug/lcov.info for in-editor coverage.

   • If you use VSCode, configuration for this should be provided when you clone the repo. Click the "watch" button in the status bar to view coverage for a file.

Implementation

See the code for full details: tools/coverage.sh.

A high level overview is:

1. The project is built and tested using instrumentation based coverage.
2. Grcov is used to aggregate these reports into lcov.info and html formats.
3. The lcov.info file can be used with the lcov command to generate summaries and get coverage information. This is used to make the summaries in our PR coverage comments.

Reading:

1. grcov readme - how to generate coverage reports.
2. rustc book - details on instrumentation based coverage.

Doc Coverage

Text: This prints a doc coverage table for all crates in the repo:

RUSTDOCFLAGS='-Z unstable-options --show-coverage' cargo +nightly doc --workspace --no-deps 

JSON: Although we don't use it yet, we can get doc coverage information as JSON. This will be useful for prettier and more useful output:

RUSTDOCFLAGS='-Z unstable-options --show-coverage --output-format json' cargo +nightly doc --workspace --no-deps 

Reading

See the unstable options section of the rustdoc book. Link.