Get grcov and install their requirements for your system.
To get a complete test report run the following commands with these env variables set. (I found some flags they suggested broke with some of our packages.)
.bashrc
export LLVM_PROFILE_FILE="your_name-%p-%m.profraw"
export RUSTDOCFLAGS="-Cpanic=abort"
RUSTFLAGS="-Zinstrument-coverage -Ccodegen-units=1 -Copt-level=0 -Coverflow-checks=off -Zpanic_abort_tests" CARGO_INCREMENTAL=0 RUSTC_BOOTSTRAP=1 cargo build
RUSTFLAGS="-Zinstrument-coverage -Ccodegen-units=1 -Copt-level=0 -Coverflow-checks=off -Zpanic_abort_tests" CARGO_INCREMENTAL=0 RUSTC_BOOTSTRAP=1 cargo test
grcov . -s . --binary-path ./target/debug/ -t html --branch --ignore-not-existing -o ./target/debug/coverage/