grcov 0.4.1

Rust tool to collect and aggregate code coverage data for multiple source files


Build Status Build status codecov

grcov collects and aggregates code coverage information for multiple source files.

This is a project initiated by Mozilla to gather code coverage results on Firefox.


  1. Download grcov from or run cargo install grcov
  2. Run grcov:
Usage: grcov DIRECTORY_OR_ZIP_FILE[...] [-t OUTPUT_TYPE] [-s SOURCE_ROOT] [-p PREFIX_PATH] [--token COVERALLS_REPO_TOKEN] [--commit-sha COVERALLS_COMMIT_SHA] [--keep-global-includes] [--ignore-not-existing] [--ignore-dir DIRECTORY] [--llvm] [--path-mapping PATH_MAPPING_FILE] [--branch] [--filter] [--add-prefix ADDED_PREFIX_PATH]
You can specify one or more directories, separated by a space.
OUTPUT_TYPE can be one of:
 - (DEFAULT) lcov for the lcov INFO format;
 - coveralls for the Coveralls specific format.
 - coveralls+ for the Coveralls specific format with function information.
 - ade for the ActiveData-ETL specific format;
 - files to only return a list of files.
SOURCE_ROOT is the root directory of the source files.
PREFIX_PATH is a prefix to remove from the paths (e.g. if grcov is run on a different machine than the one that generated the code coverage information).
ADDED_PREFIX_PATH is a prefix to add to the paths.
COVERALLS_REPO_TOKEN is the repository token from Coveralls, required for the 'coveralls' and 'coveralls+' format.
COVERALLS_COMMIT_SHA is the SHA of the commit used to generate the code coverage data.
By default global includes are ignored. Use --keep-global-includes to keep them.
By default source files that can't be found on the disk are not ignored. Use --ignore-not-existing to ignore them.
The --llvm option can be used when the code coverage information is exclusively coming from a llvm build, to speed-up parsing.
The --ignore-dir option can be used to ignore files/directories specified as globs.
The --branch option enables parsing branch coverage information.
The --filter option allows filtering out covered/uncovered files. Use 'covered' to only return covered files, 'uncovered' to only return uncovered files.

Let's see a few examples, assuming the source directory is ~/Documents/mozilla-central and the build directory is ~/Documents/mozilla-central/build.

LCOV output

grcov ~/Documents/mozilla-central/build -t lcov >

As the LCOV output is compatible with lcov, genhtml can be used to generate a HTML summary of the code coverage:

genhtml -o report/ --show-details --highlight --ignore-errors source --legend

Coveralls/Codecov output

grcov ~/Documents/FD/mozilla-central/build -t coveralls -s ~/Documents/FD/mozilla-central --token YOUR_COVERALLS_TOKEN > coveralls.json

Build & Test

In order to build, the LLVM libraries and headers are required.

cargo build

To run tests:

cargo test

Minimum requirements

  • GCC 4.9 or higher is required (if parsing coverage artifacts generated by GCC).


Published under the MPL 2.0 license.