mock.kt

// classes.kt
class Person(
    var name:String
) {
    fun getRealName():String {
        return "Real:" + this.name
    }
}

class Team {
    protected val person: Person = Person("Ben")

    var memberName: String
        get() = person.name
        set(value) {
            person.name = value
        }

    fun getPersonName():String {
        return person.getRealName()
    }
}


// classesTest.kt
import io.mockk.MockKAnnotations
import io.mockk.every
import io.mockk.impl.annotations.MockK
import io.mockk.verify
import org.junit.Before
import kotlin.test.*

class ClassesTest {
    @MockK
    private lateinit var mockPerson:Person

    @Before
    fun setup() {
        MockKAnnotations.init(this)
    }

    @Test
    fun mockGetPersonName() {
        every {
            mockPerson.getRealName()
        } returns "Albert"

        val team = Team()
        assertEquals("Albert", team.getPersonName())
    }

    @Test
    fun mockPropertyGetter() {
        every {
            mockPerson.name
        } returns "Albert"

        val team = Team()
        assertEquals("Albert", team.memberName)
    }

    @Test
    fun mockPropertySetter() {
        val team = Team()
        team.memberName = "Kim"
        verify {
            // I want to check if the setter of the person.name has been called with "Kim"
            mockPerson.name = "Kim"
        }
    }
}