NoClassDefFoundError: TestEngine with isolation=MERGED

[sormuras]

Works using isolation=NONE

Execution failed!: java.lang.NoClassDefFoundError: org/junit/platform/engine/TestEngine: org.junit.platform.engine.TestEngine

https://travis-ci.com/sormuras/mainrunner/jobs/170420282#L771

[sparsick]

Same issue when running JUnit3 tests. Workaround with isolation=NONE helps here, too.

Another workaround that also helps is

<configuration>
    <tweaks>
        <moveTestEnginesToLauncherClassLoader>false</moveTestEnginesToLauncherClassLoader>
    </tweaks>
</configuration>

[sormuras]

Version 1.1.0 will set isolation=NONE as the default mode -- perhaps remove the entire isolation level support.

/cc @rfscholte