TestCoroutineRule.kt

TestCoroutineRule.kt

import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.test.*
import org.junit.rules.TestRule
import org.junit.runner.Description
import org.junit.runners.model.Statement

@ExperimentalCoroutinesApi
class TestCoroutineRule : TestRule {
    val testCoroutineDispatcher = UnconfinedTestDispatcher()
    val testCoroutineScope = TestScope(testCoroutineDispatcher)

    override fun apply(base: Statement, description: Description?) = object : Statement() {
        @Throws(Throwable::class)
        override fun evaluate() {
            Dispatchers.setMain(testCoroutineDispatcher)

            base.evaluate()

            Dispatchers.resetMain() // reset main dispatcher to the original Main dispatcher
        }
    }
}