I think I can work around it for now by adding

kotlin {
    sourceSets {
        test.kotlin.srcDirs += 'build/generated/ksp/debugUnitTest/kotlin'
    }
}

but it seems like this was an oversight in configuring the source sets in the ksp plugin?

repro: • add a ksp processor dependency with kspTest • have the test sources cause the symbol processor to generate kotlin files • have those generated kotlin files referenced by java sources within the test sources • compilation fails with error that the java sources cannot find references to the generated kotlin (compileDebugUnitTestKotlin task)