Update

Turned out that we were excluding the wrong module. ChangingspringBootTest.exclude(mapOf("group" to "junit", "module" to "junit")) to springBootTest.exclude(mapOf("group" to "junit", "module" to "org.junit.vintage")) fixed the problem.

gradle-runner-junit5-kotlin

Since we tried to update our Gradle plugin to use Gradle 6.4 some tests that assert JUnit 5 is working have started failing.

The problem appears to be that when using the Gradle Runner to build and run a project in a test, it somehow picks junit-vintage as the test engine even though it's been excluded from the project. It can't find junit-vintage, so it falls over.

This project is a minimal implementation to demonstrate the problem.

To reproduce:

• Check out the project and run ./gradlew test

To workaround the problem:

• Switch to Gradle 6.3 with command ./gradlew wrapper --gradle-version 6.3
• Run command ./gradlew test
• (No idea why this works)

An alternative workaround:

• Switch back to Gradle 6.4!
• In function MyPlugin#addDependencies, comment out line springBootTest.exclude(mapOf("group" to "junit", "module" to "junit"))
• Run command ./gradlew test
• (The test now works because with junit 4 back on the classpath the wrongly chosen engine is now available)