coverage

---

title: "Coverage" description: "Kover-based test coverage setup + the worker-kmp 100%-coverage gate for cmp-worker-* modules."

Code Coverage (Kover)

worker-kmp uses kotlinx-kover for line-coverage measurement + enforcement. Since v3.1.3, 6 testable commonMain modules carry a hard 100% line-coverage floor; CI fails PRs that regress below it. Two additional modules (cmp-worker-scheduler, cmp-worker-compose) are test-complete but cannot opt in yet — see Known limitation: AGP 9 + Kover 0.9.1.

Quick start

# Generate aggregate HTML report
./gradlew koverHtmlReport
open build/reports/kover/html/index.html   # macOS

# Generate XML report (CI / codecov consumption)
./gradlew koverXmlReport

# Verify 100% line coverage per opted-in module (fails on regression)
./gradlew koverVerify

What's measured

Kover instruments JVM bytecode only. KMP commonMain code compiles to JVM (via jvmTest) so it IS measured. iOS, JS, and wasmJs platform actuals do NOT get coverage — see the exclusions below.

Modules in scope

Module	Status
cmp-worker-kmp	100% commonMain (gated by koverVerify)
cmp-worker-store5	100% commonMain (gated by koverVerify)
cmp-worker-storeflow	100% commonMain (gated by koverVerify)
cmp-worker-koin	100% commonMain (gated by koverVerify)
cmp-worker-sync	100% commonMain (gated by koverVerify)
cmp-worker-test	100% commonMain (gated by koverVerify)

Modules NOT in scope (with rationale)

Module	Why excluded
cmp-worker-scheduler	Test suite complete (39 @Tests across 8 commonTest files run via jvmTest) but Kover plugin NOT applied. Blocked on upstream Kover support for AGP 9's android.kotlin.multiplatform.library extension shape. Tracked by follow-up plan kover-agp9-opt-in-followup.
cmp-worker-compose	Test suite complete (21 @Tests incl. NonComposableSurfacesTest) but Kover plugin NOT applied for the same AGP 9 reason. @Composable bodies would be filter-excluded anyway; the testable non-@Composable utilities (state-mapping, request builders) are covered. Tracked by the same follow-up plan.
cmp-worker-app-annotations	Annotation-only module — no executable code to measure.
cmp-worker-android, cmp-worker-ios, cmp-worker-desktop, cmp-worker-desktop-daemon, cmp-worker-web, cmp-worker-web-push	Platform actuals; Kover only measures JVM bytecode. Tracked separately by the Tier-2 follow-up epic worker-kmp-platform-engine-tests, which adds Robolectric (Android) + Xcode-sim (iOS) + browser-test (Web) harnesses.
cmp-worker-app-ksp, cmp-worker-app-plugin	Build-tooling (KSP processor + Gradle plugin) — needs Gradle TestKit; deferred.
cmp-worker-bench, cmp-worker-migrate	Non-production tooling.
samples/*	Illustrative; not under coverage threshold.

Known limitation — AGP 9 + Kover 0.9.1

Kover 0.9.1 cannot introspect the new android.kotlin.multiplatform.library Gradle plugin extension shape that AGP 9+ uses for KMP-Android library modules. Applying id("io.github.mobilebytelabs.kover") to cmp-worker-scheduler or cmp-worker-compose fails at configuration time.

Workaround in place: the convention plugin is intentionally NOT applied to those two modules. Their tests still run via ./gradlew :cmp-worker-scheduler:jvmTest and ./gradlew :cmp-worker-compose:jvmTest; they just don't contribute to Kover aggregation.

Revisit criteria: when Kover ships a release that supports the AGP 9 KMP-Android library extension (track Kover #649 or the equivalent), bump kover in gradle/libs.versions.toml, apply id("io.github.mobilebytelabs.kover") to both modules' plugins {} blocks, and remove the explanatory comment block. The follow-up plan kover-agp9-opt-in-followup carries the full checklist.

Exclusion patterns

The root KoverConventionPlugin delegates to configureKoverRootReports() in Kover.kt, which excludes:

excludes {
    classes(
        "*.di.*",                       // Koin DI declarations
        "*.BuildConfig",                // Android-generated BuildConfig
        "*ComposableSingletons*",       // Compose generated lambda holders
        "*_*Factory*",                  // Generated factories
        "*\$ComposableLambda\$*",
        "*Preview*",                    // @Preview functions
        "*Test*",                       // Test helpers themselves
    )
    packages(
        "*.generated.*",
        "*.ksp.*",
        "*.android", "*.ios", "*.jvm", "*.js", "*.wasmJs",  // platform actuals
    )
    annotatedBy("androidx.compose.runtime.Composable")
}

The verify rule enforces:

verify {
    rule { minBound(100) }
}

This is LINE aggregation per the Kover 0.9.1 default; per-module — each opted-in module gates its own bytecode.

Adding a new module

1. Add id("io.github.mobilebytelabs.kover") to the new module's build.gradle.kts plugins {} block.
2. The convention plugin auto-registers it with the root aggregator via rootProject.dependencies.add("kover", project).
3. ./gradlew :{new-module}:koverVerify will start failing until 100% line coverage is reached.
4. If the new module is platform-heavy (mostly androidMain / iosMain / etc.), do NOT apply the plugin — add a row to the "Modules NOT in scope" table above and surface the gap in the Tier-2 follow-up epic.

Escape hatches

For provably-uncoverable lines (e.g. sealed when synthetic else branches that the bytecode verifier mis-counts as missed), two options:

1. Per-class exclusion — extend the classes(...) list in Kover.kt with the FQN. Document the reason in a code comment.
2. @ExcludeFromCoverage (future) — once the marker annotation lands, annotate the uncoverable member and reference it via the filter's annotatedBy(...).

Every escape hatch must carry a code-comment rationale and a linked issue. The quarterly maintenance pass prunes stale exclusions.

CI workflow

The Test Coverage / Kover 100% gate job at .github/workflows/test-coverage.yml runs on every PR + push to main / development. It:

1. Runs ./gradlew koverHtmlReport koverXmlReport koverVerify.
2. Uploads the aggregate HTML report as kover-html-report (14-day retention).
3. Posts the aggregate % to the PR Step Summary.

koverVerify exit ≠ 0 fails the PR. There is no soft-warn mode.

Related

• Coverage epic plan: plan-layer/project-plans/mbs/worker-kmp/active/kover-100-coverage/
• Tier-2 platform-engine tests: worker-kmp-platform-engine-tests
• Convention plugin pattern: convention-plugin.md