如何测试包含 rememberLauncherForActivityResult 的 Jetpack Compose Composable？

Question

如何测试调用rememberLauncherForActivityResult的 Android Jetpack Compose 可组合项？

例如：

import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.result.contract.ActivityResultContracts.CreateDocument
import androidx.compose.runtime.Composable
import androidx.compose.material3.Button
import androidx.compose.material3.Text

@Composable
fun PickFileButton() {
  val launcher = rememberLauncherForActivityResult(CreateDocument("text/plain")) { 
    /* do something with the returned Uri */ 
  }
  Button(onClick={launcher.launch("default_file_name.txt")}) {
    Text("Pick File") 
  }
}

单击该按钮会启动用户用来选择文件的另一个活动。

测试看起来像：

import org.junit.Rule
import org.junit.Test
import androidx.compose.ui.test.junit4.createComposeRule
import androidx.compose.ui.test.onNodeWithText
import androidx.compose.ui.test.performClick

class TestPickFileButton {
  @get:Rule val composeTestRule = createComposeRule()

  @Test
  fun testPickFileButton() {
    composeTestRule.setContent { PickFileButton() }
    composeTestRule.onNodeWithText("Pick File").performClick()
    // now Android CreateDocument activity has launched 
    // and "composeTestRule" cannot interact with this activity
    
    // rest of test eg to check the file was created
  }
}

我无法完成测试，因为外部活动已启动，我无法使用ComposeContentTestRule object 与此活动进行交互。

Answer 1

该解决方案涉及使用CompositionLocalProvider覆盖默认的ActivityResultRegistry 。 这允许您使用ActivityResultRegistry.dispatchResult发送自定义响应，而不是启动活动。

我必须阅读CreateDocument合同的源代码才能了解预期返回的Intent类型。

这个特定问题的有效解决方案是：

import android.app.Activity
import android.content.Intent
import android.net.Uri
import androidx.activity.compose.LocalActivityResultRegistryOwner
import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.result.ActivityResultRegistry
import androidx.activity.result.ActivityResultRegistryOwner
import androidx.activity.result.contract.ActivityResultContract
import androidx.activity.result.contract.ActivityResultContracts.CreateDocument
import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
import androidx.compose.ui.test.junit4.createComposeRule
import androidx.compose.ui.test.onNodeWithText
import androidx.compose.ui.test.performClick
import androidx.core.app.ActivityOptionsCompat
import androidx.core.net.toFile
import org.junit.Rule
import org.junit.Test

@Composable
fun PickFileButton() {
  val launcher =
      rememberLauncherForActivityResult(CreateDocument("text/plain")) {
        /* do something with the returned Uri */
      }
  Button(onClick = { launcher.launch("default_file_name.txt") }) { Text("Pick File") }
}

class TestPickFileButton {
  @get:Rule val composeTestRule = createComposeRule()

  @Test
  fun testPickFileButton() {

    val testUri = Uri.parse("uri_string_to_return")

    composeTestRule.setContent {

      // ActivityResultRegistry is responsible for handling the 
      // contracts and launching the activity
      val registryOwner = ActivityResultRegistryOwner {
        object : ActivityResultRegistry() {
          override fun <I : Any?, O : Any?> onLaunch(
              requestCode: Int,
              contract: ActivityResultContract<I, O>,
              input: I,
              options: ActivityOptionsCompat?
          ) {
            // don't launch an activity, just respond with the test Uri
            val intent = Intent().setData(testUri)
            this.dispatchResult(requestCode, Activity.RESULT_OK, intent)
          }
        }
      }

      CompositionLocalProvider(LocalActivityResultRegistryOwner provides registryOwner) {
        // any composable inside this block will now use our mock ActivityResultRegistry
        PickFileButton()
      }
    }


    composeTestRule.onNodeWithText("Pick File").performClick()
    // no activity is launched, PickFileButton will received testUri as a respose.

    // rest of test eg to check the file was created
    assert(testUri.toFile().exists())
  }
}

资料来源： Kotlin Lang Slack Chat中的讨论， Android 存储库中的 ActivityResultRegistryTest ， CompositionLocalProvider