bin+lib grcov

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

2 unstable releases

0.3.0 Oct 9, 2018
0.2.3 Oct 5, 2018

#7 in #coverage

Download history 19/week @ 2018-10-10

6 downloads per month

MPL-2.0 license



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 https://github.com/mozilla/grcov/releases 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 > lcov.info

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 lcov.info

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.


~156K SLoC

  • build build.rs
  • build cc 1.0
  • dev regex 1.0