在 kotlin 单元测试中如何分配 lateinit var答案

【问题标题】：In kotlin unit test how the assign lateinit var在 kotlin 单元测试中如何分配 lateinit var
【发布时间】：2017-10-05 07:00:10
【问题描述】：

@RunWith(MockitoJUnitRunner::class)
class RoundingTest {
    lateinit var rounding: (Double) -> Double

 @Before
fun initValues(){
    rounding(17.25)
}

    @Test
    fun checkRounding() {
        rounding(17.25)

       var rounding = MyRoundingClass.roundValue(Myobject);
        Assert.assertEquals(17.23, rounding)
    }
}
object MyRoundingClass{
fun roundValue(myObject: MyObject): (Double) -> Double {
        return when (myObject.isrouding?.needed) {
            ROUND_DOWN -> { value -> roundDown(BigDecimal.valueOf(value)) }
            else ->
                // no rounding
                { value -> value }
        }
    }
}

在roundValue 方法中，value 参数是从My Fragment 中的rounding(17.25) 分配的，它运行良好，但测试它不起作用。它给了我以下错误 kotlin.UninitializedPropertyAccessException：lateinit 属性舍入尚未初始化

at com.appetizeactivate.android.rounding.RoundingStatergyTest.checkRoundingWithNone(RoundingTest.kt:23)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:117)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:262)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:84)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

【问题讨论】：

标签： unit-testing kotlin

【解决方案1】：

看来你需要更改rounding的类型并使其成为

 lateinit var rounding: () -> Double

并将其分配为

 rounding = { 17.25 }

然后将其用作rounding()（注意括号）。

【讨论】：