JoseAlcerreca

@Test
fun loginScreen_onContinueClick_welcomeDisplayed() {
    composeTestRule.onNodeWithText("Continue¨).performClick()

    composeTestRule.waitUntilDoesNotExist(hasText("Loading"))

    composeTestRule.onNodeWithText("Welcome").assertExists()
}

JoseAlcerreca

@Test
fun loginScreen_onContinueClick_welcomeDisplayed() {
    composeTestRule.onNodeWithText("Continue¨).performClick()

    // Screen still shows "Loading"

    composeTestRule.onNodeWithText("Welcome").assertExists()  // FAILS!
}

JoseAlcerreca

class MyViewModel(repository…) {
    val data = flow{
        ...
        emitAll(repository.observeData())
    }
}

JoseAlcerreca

@Composable
fun MyScreen(val viewModel: MyViewModel = viewModel()) {
    val data by viewModel.data.collectAsState("Loading")
    Text(greeting)
}

JoseAlcerreca

composeTestRule.waitUntilExists(hasText("Continue"))

JoseAlcerreca

// Copyright 2022 Google LLC.
// SPDX-License-Identifier: Apache-2.0

fun ComposeContentTestRule.waitUntilExists(
    matcher: SemanticsMatcher,
    timeoutMillis: Long = 1_000L
) {
    return this.waitUntilNodeCount(matcher, 1, timeoutMillis)
}

JoseAlcerreca

// Copyright 2022 Google LLC.
// SPDX-License-Identifier: Apache-2.0

fun ComposeContentTestRule.waitUntilNodeCount(
    matcher: SemanticsMatcher,
    count: Int,
    timeoutMillis: Long = 1_000L
) {
    this.waitUntil(timeoutMillis) {
        this.onAllNodes(matcher).fetchSemanticsNodes().size == count

JoseAlcerreca

// Click on a button
composeTestRule.onNodeWithText("Continue").performClick()

// Wait until there's one element with a "Welcome" text
composeTestRule.waitUntil {
    composeTestRule
        .onAllNodesWithText("Welcome")
        .fetchSemanticsNodes().size == 1
}

JoseAlcerreca

composeTestRule.onNodeWithText("Continue¨) .performClick()
Thread.sleep(2000)  // don't do this
composeTestRule.onNodeWithText("Welcome").assertExists()

JoseAlcerreca

class MyRepo(dataSource: MyDataSource) {
    suspend fun getItems() {
        idlingResource.setBusy() // App is busy… test must wait.

        val result = dataSource.getTasks()

        idlingResource.setIdle() // App is idle, ready for next operation.
        return result
    }
}