Kover

What Kover is

Kover is a free toolset for measuring test coverage in Kotlin code compiled for JVM and Android. It includes Gradle and Maven plugins, a command-line interface, offline instrumentation, a JVM agent, and a features artifact. Its Gradle plugin creates HTML and XML reports and can apply coverage verification rules. Coverage types include line, instruction, and branch; supported languages are Kotlin and Java, and the listed report formats also include IC. The plugin works with Kotlin JVM, Kotlin Android, Kotlin Multiplatform, and the com.android.kotlin.multiplatform.library plugins. It can handle mixed Kotlin and Java sources and can use JaCoCo instead for coverage measurement and report generation. For Android, Kover supports build variants and collects coverage from host tests. It does not collect coverage from instrumented tests running on an Android device, and the Gradle plugin does not support JavaScript or native targets. It instruments classes as they load into the JVM during tests, which may affect performance or concurrent tests. The Gradle plugin requires Gradle 6.8.3 or later, JVM 1.7 or later for tests, and Android Gradle Plugin 7.0.0 or later. Kotlin maintains the project, which uses the Apache-2.0 license.

Who it suits

Kover suits Kotlin teams that need coverage reports or verification rules for JVM and Android tests, including projects with mixed Kotlin and Java sources. Its Maven and Gradle plugins, command-line interface, and JVM tooling provide several ways to work with coverage.

Limits

The Gradle plugin does not support JavaScript or native targets and does not collect coverage from instrumented tests running on an Android device. Its instrumentation may reduce performance or affect concurrent tests. The Kover Aggregated Plugin is an early prototype recommended only for test or pet projects.

Getting started

1. Open the Kover website.
2. Use the Gradle or Maven plugin, command-line interface, or other included tool.
3. For the Gradle plugin, use Gradle 6.8.3 or later and Android Gradle Plugin 7.0.0 or later where applicable.
4. Run tests with JVM 1.7 or later.
5. Generate coverage reports or configure verification rules with the Gradle plugin.

Verdict

Choose Kover for free coverage measurement and verification in Kotlin JVM or Android projects, especially when you need support for mixed Kotlin and Java sources. Look elsewhere if you need Gradle-plugin coverage for JavaScript or native targets, or coverage from instrumented Android-device tests.