Kotlin: This show how to test Event Handlers with JUnit & 'Mockito-kotlin'

EventHandlerTest.kt

package vfx.kotlin

import com.nhaarman.mockito_kotlin.argumentCaptor
import com.nhaarman.mockito_kotlin.mock
import com.nhaarman.mockito_kotlin.verify
import org.junit.Assert
import org.junit.Test

data class Pizza(val name: String)

object PizzaService {

    interface PizzaEvent {
        fun pizzaAvailable(pizza: Pizza)
    }

    var listener: PizzaEvent? = null

    fun orderPizza(name: String) {
        listener?.pizzaAvailable(Pizza(name))
    }
}

class VfxModelTestAgain {

    @Test
    fun testOrderPizzaWithArgumentMatcher() {

        val pizzaName = "Margarita"
        val service = PizzaService
        val event = mock<PizzaService.PizzaEvent>()
        service.listener = event

        service.orderPizza(pizzaName)

        val captor = argumentCaptor<Pizza>()
        verify(event).pizzaAvailable(captor.capture())
        val capturedPizza = captor.firstValue
        Assert.assertEquals(pizzaName, capturedPizza.name)
    }

}

***

{pom.xml}

see dependencies:

...

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.nhaarman</groupId>
            <artifactId>mockito-kotlin</artifactId>
            <version>1.5.0</version>
        </dependency>

...