cargo-coverage-annotations-0.1.0 is not a library.

cargo-coverage-annotations

Ensure annotations in code match actual coverage.

Installing

To install:

cargo install cargo-coverage-annotations

Running

To run on a cargo project in the current working directory:

cargo tarpaulin --out Xml
cargo coverage-annotations

This will generate a cobertura.xml file containing coverage information, then verify that the annotations in the code match the actual coverage.

TODO: support additional coverage file formats (kcov, gcov).

Checking coverage annotations on a CI server

To keep your code base clean, it can be helpful to fail the CI build when the code contains wrong coverage annotations. To achieve this, include `cargo coverage-annotations`` in your CI build steps. For example, a minimal Travis setup might look like this:

language: rust
cache: cargo
before_script:
- export PATH="$PATH:$HOME/.cargo/bin"
- which cargo-tarpaulin || cargo install cargo-tarpaulin
- which cargo-coverage-annotations || cargo install cargo-coverage-annotations
script:
- cargo build
- cargo test
- cargo tarpaulin --out Xml
- cargo coverage-annotations

Note that using cache: cargo is optional but highly recommended to speed up the installation.

Coverage annotations

Coverage annotations are comments that indicate the coverage status of the code lines. By default, code lines are assumed to be covered by tests. Lines that are not tested are expected to end with an explicit // NOT TESTED comment. It is also possible to mark a line with a // MAYBE TESTED comment in special cases (for example, lines that only execute on some platforms).

Sometimes a whole block of lines needs to be marked. In this case, it is possible to surround such lines with // BEGIN NOT TESTED ... // END NOT TESTED comments (or // BEGIN MAYBE TESTED ... // END MAYBE TESTED). Inside such regions, it is possible to override the annotation for specific lines with // TESTED, // NOT TESTED or // MAYBE TESTED comments.

Finally, some files might not be tested at all. In this case, they must contain in one of their lines a // FILE NOT TESTED or // FILE MAYBE TESTED comment. This includes examples files.

Coverage annotations are only used for files in the src directory. They ensure that when reading the code, one is aware of what is and is not covered by tests. Of course, line coverage is only the most basic form of coverage tracking; that said, tracking it at each step is surprisingly effective in isolating cases when the code does not behave as expected.

License