Skip to main content

Kotlin & Kotest Support

test-order has limited but tested support for Kotlin projects using Kotest with the JUnit Platform runner.

What Works​

  • ✅ Kotest StringSpec, FunSpec, and other spec styles via JUnit Platform runner (kotest-runner-junit5)
  • ✅ Kotlin source detection in src/main/kotlin and src/test/kotlin
  • ✅ Dependency tracking on compiled Kotlin bytecode (no language-specific handling needed)
  • ✅ Change detection on .kt source files
  • ✅ Learn mode builds dependency indices for Kotest tests
  • ✅ Class-level test ordering applied to Kotest test specs

Limitations​

  • 🔶 Method-level ordering: Kotest's DSL-based test definitions map to a single test spec class; method-level ordering may not align with test case structure.
  • 🔶 Inline functions: Kotlin inline fun calls are erased by the compiler (bytecode is copied into the call site). In MEMBER mode (the default), the agent cannot track the inlined call, so dependency precision is reduced. Consider switching to CLASS mode for Kotlin projects — it tracks at class level and is not affected by inlining: -Dtestorder.instrumentation.mode=CLASS.
  • 🔶 Tested with: Kotest 5.9.1 + JUnit Platform runner. Other Kotest configurations may behave differently.
  • 🔶 Not supported: Kotest tests run directly (without JUnit Platform runner) will not be reordered.

Maven Example​

<dependency>
    <groupId>io.kotest</groupId>
    <artifactId>kotest-runner-junit5-jvm</artifactId>
    <version>5.9.1</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>io.kotest</groupId>
    <artifactId>kotest-assertions-core-jvm</artifactId>
    <version>5.9.1</version>
    <scope>test</scope>
</dependency>

Verify Kotest integration with:

mvn clean test-order:auto test

Working Examples​