`-t html` works with `-o ./target/debug/coverage/`, but `-t lcov` doesn't

[Saurabh]

From README:

Generate a html coverage report like this:

grcov . -s . --binary-path ./target/debug/ -t html --branch --ignore-not-existing -o ./target/debug/coverage/

N.B.: The --binary-path argument is only necessary for source-based coverage.

You can see the report in target/debug/coverage/index.html.

(or alternatively with -t lcov grcov will output a lcov compatible coverage report that you could then feed into lcov's genhtml command).

indicates that using

grcov . -s . --binary-path ./target/debug/ -t lcov --branch --ignore-not-existing -o ./target/debug/coverage/

will create an LCOV file in directory ./target/debug/coverage/, but the directory doesn't actually get created.

The above command throws error:

[ERROR] A panic occurred at /home/saurabh/.local/share/rust/cargo/registry/src/github.com-1ecc6299db9ec823/grcov-0.8.18/src/output.rs:59: Cannot create the file ./target/debug/coverage/ to dump coverage data.

Steps to reproduce

rustup component add llvm-tools-preview
export RUSTFLAGS="-Cinstrument-coverage"
cargo test
grcov . -s . --binary-path ./target/debug/ -t lcov --branch --ignore-not-existing -o ./target/debug/coverage/

[Marco Castelluccio]

In case of lcov, the path must be a file and not a directory.

[Saurabh]

I tried running

grcov . -s . --binary-path ./target/debug/ -t lcov --branch --ignore-not-existing -o ./target/debug/

and it works. The path is a directory.

I replaced the 4th command in Steps to reproduce with the above.