JUnit断言一个Activity是接口的实现

Question

我有一个实现了名为IMeetingRoomDelegate的委托接口的Android活动。

interface IMeetingRoomDelegate {
    fun onMeetingRoomFragmentClicked(homeFragment: MeetingRoomHomeFragment, meetingRoom: ParcelableMeetingRoomData)
}

我希望始终确保我的Activity是IMeetingRoomDelegate的实现。 在Kotlin中，我该如何检查它呢？目前我有以下代码：

@RunWith(AndroidJUnit4::class)
class GivenTheMainActivityIsLoaded {

    @get:Rule
    val activityRule =  ActivityTestRule<MainActivity>(MainActivity::class.java)
    private lateinit var mainActivity: MainActivity

    @Before
    fun setup() {
        this.mainActivity = activityRule.activity
    }

    @Test
    fun thenThereShouldAlsoBeAnInstanceOfIMeetingRoomDelegatePresent() {
        assertTrue(implementsInterface(this.mainActivity::class.java))
    }

    private fun implementsInterface(interf: Class<*>): Boolean {
        return interf is IMeetingRoomDelegate
    }
}

我尝试自己查找问题，但测试运行程序几乎没有提供任何实质性的信息。

错误信息：

java.lang.AssertionError
at org.junit.Assert.fail(Assert.java:86)
at org.junit.Assert.assertTrue(Assert.java:41)
at org.junit.Assert.assertTrue(Assert.java:52)
at activities.GivenTheMainActivityIsLoaded.thenThereShouldAlsoBeAnInstanceOfIMeetingRoomDelegatePresent(MainActivitySpec.kt:54)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:527)
at org.junit.rules.RunRules.evaluate(RunRules.java:20)
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 androidx.test.runner.AndroidJUnit4.run(AndroidJUnit4.java:104)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:27)
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$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
at androidx.test.internal.runner.TestExecutor.execute(TestExecutor.java:56)
at androidx.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:392)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:2189)

Tests ran to completion.

- Marc Freeman

Answer 1

您可以使用具体化泛型（reified generics）替代反射的断言：

@Test
fun thenThereShouldAlsoBeAnInstanceOfIMeetingRoomDelegatePresent() {
    assertTrue(this.mainActivity.implementsInterface())
}

private inline fun <reified T> T.implementsInterface(): Boolean {
    return this is IMeetingRoomDelegate
}

- Animesh Sahu

---

@MarcFreeman，你能确认一下这个活动实现了接口吗？因为对我来说它运行得很好！ - Animesh Sahu

一个简单的例子，使用层次结构返回true。https://pl.kotl.in/SG06ZxRbX - Animesh Sahu

另外，抱歉修改了你的答案，我还没完全清醒。 - Marc Freeman

澄清上述声明：我在发布后的1分钟内编辑了答案，OP可能没有更新他的浏览器，我只是将String放入implementsInterface()中，因为我正在使用我的IDE进行测试。 - Animesh Sahu

我还重新修改了答案，使其尽可能通用：inline fun <reified T, reified U> T.implementsInterface(): Boolean { return this is U }用法： assertTrue(this.mainActivity.implementsInterface<MainActivity ,IMeetingRoomDelegate>()) - Marc Freeman