Coroutine Mockk Example

CoroutinesTest.kt

import io.mockk.coEvery
import io.mockk.coVerify
import io.mockk.mockk
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import org.junit.Test

class CoroutinesTest {

    @Test
    fun `coroutines test`() {
        val arithmetic = mockk<Arithmetic>(relaxed = true)
        coEvery { arithmetic.getNumber() } returns 5

        GlobalScope.launch {
            arithmetic.doMath()
        }

        coVerify { arithmetic.getNumber() }
    }

    class Arithmetic {
        suspend fun doMath(): Int = 1 + 2 + getNumber()

        suspend fun getNumber(): Int {
            delay(1000)
            return 3
        }
    }
}