android - 如何测试使用 ActivityResult API 的 Activity？

Question

docs在测试 Fragments 时非常好，但是没有关于如何测试使用 ActivityResult 的 Activity 的信息。

我们应该如何在 Activity 测试中重写 activityResultRegistry？

Answer 1

将您的合约写入单独的文件中，以便您可以轻松测试合约并在运行时提供您自己的 ActivityResultRegistry 来伪造预期结果。实际上调用真实的合约来从 Activity 中进行测试是不好的做法。设计合约的核心目的之一是将 Activity 代码与 onActicityResults 解耦

class ImageContract(registry: ActivityResultRegistry) {

    private val contractUriResult : MutableLiveData<Uri>  = MutableLiveData(null)

    private val getPermission = registry.register(REGISTRY_KEY, ActivityResultContracts.GetContent()) { uri ->
        contractUriResult.value = uri
    }

    fun getImageFromGallery(): LiveData<Uri> {
        getPermission.launch("image/*")
        return contractUriResult
    }

    companion object {
        private const val REGISTRY_KEY = "Image Picker"
    }
}

在您的 Activity 中

 ImageContractHandler(activityResultRegistry).getImageFromGallery().observe(this, {
      it?.let { u ->
           backgroundImageView.setImageURI(u)
      }
 })

在您的测试中

@Test
fun activityResultTest() {

    // Create an expected result URI
    val testUrl = "file//dummy_file.test"
    val expectedResult = Uri.parse(testUrl)

    // Create the test ActivityResultRegistry
    val testRegistry = object : ActivityResultRegistry() {
        override fun <I, O> onLaunch(
            requestCode: Int,
            contract: ActivityResultContract<I, O>,
            input: I,
            options: ActivityOptionsCompat?
        ) {
            dispatchResult(requestCode, expectedResult)
        }
    }

    val uri = ImageContractHandler(testRegistry).getImageFromGallery().getOrAwaitValue()
    assert(uri == expectedResult)
}

用于在 Tests 中的同一线程上监听 LiveData，这是一个著名的 livedata 测试扩展

fun <T> LiveData<T>.getOrAwaitValue(
    time: Long = 2,
    timeUnit: TimeUnit = TimeUnit.SECONDS,
    afterObserve: () -> Unit = {}
): T {
    var data: T? = null
    val latch = CountDownLatch(1)
    val observer = object : Observer<T> {
        override fun onChanged(o: T?) {
            data = o
            latch.countDown()
            <a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="d2a6babba192b5b7a69da093a5b3bba684b3bea7b7fca0b7bfbda4b79db0a1b7a0a4b7a0" rel="noreferrer noopener nofollow">[email protected]</a>(this)
        }
    }
    this.observeForever(observer)

    afterObserve.invoke()

    // Don't wait indefinitely if the LiveData is not set.
    if (!latch.await(time, timeUnit)) {
        this.removeObserver(observer)
        throw TimeoutException("LiveData value was never set.")
    }

    @Suppress("UNCHECKED_CAST")
    return data as T
}