模拟返回 void 返回类型的存根答案

【问题标题】：mocking stubs that return a void return type模拟返回 void 返回类型的存根
【发布时间】：2019-01-15 07:58:52
【问题描述】：

我正在尝试测试以下课程。我遇到问题的方法是showScollerView，因为我试图对行为进行存根/模拟，然后在测试中验证行为。

class CustomScrollerView @JvmOverloads constructor(
        context: Context,
        attributeSet: AttributeSet? = null,
        styleAttributes: Int = 0)
    : ConstraintLayout(context, attributeSet, styleAttributes) {

    private var fragment: ConstraintLayout by Delegates.notNull()
    private var layoutResEnding: Int = 0
    private val transition = ChangeBounds()
    private val constraintSet = ConstraintSet()
    private var isShowing = false

    init {
        View.inflate(context, R.layout.overview_scroller_view, this)
        transition.interpolator = AccelerateInterpolator()
        transition.duration = 300
    }

    fun <L: ConstraintLayout> setView(view: L) {
        fragment = view
    }

    fun setLayoutResourceFinish(@LayoutRes id: Int) {
        layoutResEnding = id
    }

    fun showScrollerView() {
        constraintSet.clone(context, layoutResEnding)
        TransitionManager.beginDelayedTransition(fragment, transition)
        constraintSet.applyTo(fragment)
        isShowing = true
    }

    fun isScrollViewShowing() = isShowing
}

这是测试类

class CustomScrollerViewTest: RobolectricTest() {
    @Mock
    lateinit var constraintSet: ConstraintSet
    @Mock
    lateinit var constraintLayout: ConstraintLayout

    private var customScrollerView: CustomScrollerView by Delegates.notNull()

    @Before
    fun setup() {
        customScrollerView = CustomScrollerView(RuntimeEnvironment.application.baseContext)
    }

    @Test
    fun `test that CustomScrollerView is not null`() {
        assertThat(customScrollerView).isNotNull()
    }

    @Test
    fun `test that the scrollerView is shown`() {
        doNothing().`when`(constraintSet.clone(RuntimeEnvironment.application.baseContext, R.layout.fragment)) /* Error here */
        doNothing().`when`(constraintSet).applyTo(constraintLayout)

        customScrollerView.setLayoutResourceFinish(R.layout.fragment)
        customScrollerView.setView(constraintLayout)
        customScrollerView.showScrollerView()

        assertThat(customScrollerView.isScrollViewShowing()).isEqualTo(true)
        verify(constraintSet).applyTo(constraintLayout)
        verify(constraintSet).clone(RuntimeEnvironment.application.baseContext, R.layout.fragment)
    }
}

我在这一行得到错误：

doNothing().when(constraintSet.clone(RuntimeEnvironment.application.baseContext, R.layout.fragment))

这是实际的错误信息：

此处检测到未完成的存根： -> 在 com.nhaarman.mockito_kotlin.MockitoKt.doNothing(Mockito.kt:108)

例如thenReturn() 可能会丢失。正确的存根示例：当（模拟。isOk（））。然后返回（真）； when(mock.isOk()).thenThrow(异常); doThrow(exception).when(mock).someVoidMethod(); 提示： 1. 缺少 thenReturn() 2.您正在尝试存根不支持的最终方法 3：如果完成，您将在“thenReturn”指令之前存根另一个模拟的行为

【问题讨论】：

标签： android kotlin mockito

【解决方案1】：

你得到错误的那一行应该是：

doNothing().`when`(constraintSet).clone(RuntimeEnvironment.application.baseContext, R.layout.fragment)

就像 javadoc here 中的示例：

List list = new LinkedList();
List spy = spy(list);

//let's make clear() do nothing
doNothing().when(spy).clear();

spy.add("one");

//clear() does nothing, so the list still contains "one"
spy.clear();

【讨论】：