zig-code-coverage

Example repo that show how to generate code coverage in Zip

Ubuntu setup

kcov was only added in Ubuntu 25.04 so if you are running Ubuntu 24.04, then you need to add that as a source:

/etc/apt/sources.list.d/plucky.sources (For x86_64):

Types: deb
URIs: http://archive.ubuntu.com/ubuntu/
Suites: plucky plucky-updates plucky-backports
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
 
Types: deb
URIs: http://security.ubuntu.com/ubuntu/
Suites: plucky-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

/etc/apt/sources.list.d/plucky.sources (For arm64):

Types: deb
URIs: http://ports.ubuntu.com/ubuntu-ports/
Suites: plucky plucky-updates plucky-backports
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
 
Types: deb
URIs: http://ports.ubuntu.com/ubuntu-ports/
Suites: plucky-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg

Set low priority for all packages in plucky expect for kcov:

/etc/apt/preferences.d/plucky-pin:
Package: *
Pin: release n=plucky
Pin-Priority: -10
 
Package: kcov
Pin: release n=plucky
Pin-Priority: 500

Install kcov and tooling needed for installing zig:

apt-get install -qq --no-install-recommends -y curl xz-utils ca-certificates kcov minisign git

Installing zig and testing

Install zig:

# For x86-64
curl -sSL --fail -o zig.tar.xz "https://ziglang.org/download/0.15.1/zig-x86_64-linux-0.15.1.tar.xz"
# For arm64
curl -sSL --fail -o zig.tar.xz "https://ziglang.org/download/0.15.1/zig-aarch64-linux-0.15.1.tar.xz"
# Extract and add zig to path
mkdir -p /usr/local/zig
tar -xf zig.tar.xz -C /usr/local/zig --strip-components=1
export PATH=/usr/local/zig:$PATH

Clone repo:

git clone https://github.com/tlbdk/zig-code-coverage.git
cd zig-code-coverage

Build coverage and print coverage file:

zig build coverage
cat zig-out/coverage/cov.xml |grep line-rate

Expected output:

$ zig build coverage
coverage
└─ install generated/
   └─ run /usr/bin/kcov (.) stderr
1/3 main.test.use other module...OK
2/3 main.test.fuzz example...OK
3/3 main.test_0...OK
All 3 tests passed.
1 fuzz tests found.
$ cat zig-out/coverage/cov.xml |grep line-rate
<coverage line-rate="0.714" lines-covered="10" lines-valid="14" branch-rate="1.0" branches-covered="1.0" branches-rate="1.0" complexity="1.0" version="1.9" timestamp="1759229184">
                <package name="test" line-rate="0.714" lines-covered="10" lines-valid="14" branch-rate="1.0" complexity="1.0">
                                <class name="root_zig__0" filename="root.zig" branch-rate="1.0" complexity="1.0" line-rate="0.500">
                                <class name="main_zig__1" filename="main.zig" branch-rate="1.0" complexity="1.0" line-rate="0.800">

Testing with docker

Create builder that allows kcov to run:

docker buildx create --name insecure-builder --buildkitd-flags "--allow-insecure-entitlement security.insecure"

Build container:

docker buildx build  --progress plain  --builder insecure-builder --allow security.insecure .

VSCode setup

settings.json:

{
    // MacOS
    "lldb-dap.executable-path": "/Library/Developer/CommandLineTools/usr/bin/lldb-dap",
    // Ubuntu 24.04
    "lldb-dap.executable-path": "/usr/bin/lldb-dap-18",
    // Windows 
    "lldb-dap.executable-path": "C:/Program Files/LLVM/bin/lldb-dap.exe",
    "zig.debugAdapter": "lldb-dap",
    "[zig]": {
        "editor.formatOnSave": true,
    },
    "zig.testArgs": [
        "build",
        "test",
        "-Dtest-filter=${filter}"
    ],
     "zig.debugTestArgs": [
        "build",
        "debug-test-unit",
       "-Dtest-filter=${filter}",
    ],
    "zig.buildOnSaveProvider": "zls"
}