Error calling Dispatchers.setMain() in unit test

Try adding core as a dependency on your test. It solved the problem for me.

testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.1.0")

Turned out issue was I was using older version of kotlinx-coroutines-core dependency. When I updated to v1.1.0 it worked (thanks @vigit for helping trigger that realisation!)