Add Android testing skill for Claude (#6370)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
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# Testing Android Code Skill
Quick-reference guide for writing and reviewing tests in the Bitwarden Android codebase.
## Purpose
This skill provides tactical testing guidance for Bitwarden-specific patterns. It focuses on base test classes, test utilities, and common gotchas unique to this codebase rather than general testing concepts.
## When This Skill Activates
The skill automatically loads when you ask questions like:
- "How do I test this ViewModel?"
- "Why is my Bitwarden test failing?"
- "Write tests for this repository"
Or when you mention terms like: `BaseViewModelTest`, `BitwardenComposeTest`, `stateEventFlow`, `bufferedMutableSharedFlow`, `FakeDispatcherManager`, `createMockCipher`, `asSuccess`
## What's Included
| File | Purpose |
|------|---------|
| `SKILL.md` | Core testing patterns and base class locations |
| `references/test-base-classes.md` | Detailed base class documentation |
| `references/flow-testing-patterns.md` | Turbine patterns for StateFlow/EventFlow |
| `references/critical-gotchas.md` | Anti-patterns and debugging tips |
| `examples/viewmodel-test-example.md` | Complete ViewModel test example |
| `examples/compose-screen-test-example.md` | Complete Compose screen test |
| `examples/repository-test-example.md` | Complete repository test with mocks |
## Patterns Covered
1. **BaseViewModelTest** - Automatic dispatcher setup with `stateEventFlow()` helper
2. **BitwardenComposeTest** - Pre-configured with all managers and theme
3. **BaseServiceTest** - MockWebServer setup for network testing
4. **Turbine Flow Testing** - StateFlow (replay) vs EventFlow (no replay)
5. **Test Data Builders** - 35+ `createMock*` functions with `number: Int` pattern
6. **Fake Implementations** - FakeDispatcherManager, FakeConfigDiskSource
7. **Result Type Testing** - `.asSuccess()`, `.asFailure()`, `assertCoroutineThrows`
## Quick Start
For comprehensive architecture and testing philosophy, see:
- `docs/ARCHITECTURE.md`

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---
name: testing-android-code
description: This skill should be used when writing or reviewing tests for Android code in Bitwarden. Triggered by "BaseViewModelTest", "BitwardenComposeTest", "BaseServiceTest", "stateEventFlow", "bufferedMutableSharedFlow", "FakeDispatcherManager", "expectNoEvents", "assertCoroutineThrows", "createMockCipher", "createMockSend", "asSuccess", "Why is my Bitwarden test failing?", or testing questions about ViewModels, repositories, Compose screens, or data sources in Bitwarden.
version: 1.0.0
---
# Testing Android Code - Bitwarden Testing Patterns
**This skill provides tactical testing guidance for Bitwarden-specific patterns.** For comprehensive architecture and testing philosophy, consult `docs/ARCHITECTURE.md`.
## Test Framework Configuration
**Required Dependencies:**
- **JUnit 5** (jupiter), **MockK**, **Turbine** (app.cash.turbine)
- **kotlinx.coroutines.test**, **Robolectric**, **Compose Test**
**Critical Note:** Tests run with en-US locale for consistency. Don't assume other locales.
---
## A. ViewModel Testing Patterns
### Base Class: BaseViewModelTest
**Always extend `BaseViewModelTest` for ViewModel tests.**
**Location:** `ui/src/testFixtures/kotlin/com/bitwarden/ui/platform/base/BaseViewModelTest.kt`
**Benefits:**
- Automatically registers `MainDispatcherExtension` for `UnconfinedTestDispatcher`
- Provides `stateEventFlow()` helper for simultaneous StateFlow/EventFlow testing
**Pattern:**
```kotlin
class ExampleViewModelTest : BaseViewModelTest() {
private val mockRepository: ExampleRepository = mockk()
private val savedStateHandle = SavedStateHandle(mapOf(KEY_STATE to INITIAL_STATE))
@Test
fun `ButtonClick should fetch data and update state`() = runTest {
coEvery { mockRepository.fetchData(any()) } returns Result.success("data")
val viewModel = ExampleViewModel(savedStateHandle, mockRepository)
viewModel.stateFlow.test {
assertEquals(INITIAL_STATE, awaitItem())
viewModel.trySendAction(ExampleAction.ButtonClick)
assertEquals(INITIAL_STATE.copy(data = "data"), awaitItem())
}
coVerify { mockRepository.fetchData(any()) }
}
}
```
**For complete examples:** See `references/test-base-classes.md`
### StateFlow vs EventFlow (Critical Distinction)
| Flow Type | Replay | First Action | Pattern |
|-----------|--------|--------------|---------|
| StateFlow | Yes (1) | `awaitItem()` gets current state | Expect initial → trigger → expect new |
| EventFlow | No | `expectNoEvents()` first | expectNoEvents → trigger → expect event |
**For detailed patterns:** See `references/flow-testing-patterns.md`
---
## B. Compose UI Testing Patterns
### Base Class: BitwardenComposeTest
**Always extend `BitwardenComposeTest` for Compose screen tests.**
**Location:** `app/src/test/kotlin/com/x8bit/bitwarden/ui/platform/base/BitwardenComposeTest.kt`
**Benefits:**
- Pre-configures all Bitwarden managers (FeatureFlags, AuthTab, Biometrics, etc.)
- Wraps content in `BitwardenTheme` and `LocalManagerProvider`
- Provides fixed Clock for deterministic time-based tests
**Pattern:**
```kotlin
class ExampleScreenTest : BitwardenComposeTest() {
private var haveCalledNavigateBack = false
private val mutableEventFlow = bufferedMutableSharedFlow<ExampleEvent>()
private val mutableStateFlow = MutableStateFlow(DEFAULT_STATE)
private val viewModel = mockk<ExampleViewModel>(relaxed = true) {
every { eventFlow } returns mutableEventFlow
every { stateFlow } returns mutableStateFlow
}
@Before
fun setup() {
setContent {
ExampleScreen(
onNavigateBack = { haveCalledNavigateBack = true },
viewModel = viewModel,
)
}
}
@Test
fun `on back click should send BackClick action`() {
composeTestRule.onNodeWithContentDescription("Back").performClick()
verify { viewModel.trySendAction(ExampleAction.BackClick) }
}
}
```
**Note:** Use `bufferedMutableSharedFlow` for event testing in Compose tests. Default replay is 0; pass `replay = 1` if needed.
**For complete base class details:** See `references/test-base-classes.md`
---
## C. Repository and Service Testing
### Service Testing with MockWebServer
**Base Class:** `BaseServiceTest` (`network/src/testFixtures/`)
```kotlin
class ExampleServiceTest : BaseServiceTest() {
private val api: ExampleApi = retrofit.create()
private val service = ExampleServiceImpl(api)
@Test
fun `getConfig should return success when API succeeds`() = runTest {
server.enqueue(MockResponse().setBody(EXPECTED_JSON))
val result = service.getConfig()
assertEquals(EXPECTED_RESPONSE.asSuccess(), result)
}
}
```
### Repository Testing Pattern
```kotlin
class ExampleRepositoryTest {
private val fixedClock: Clock = Clock.fixed(
Instant.parse("2023-10-27T12:00:00Z"),
ZoneOffset.UTC,
)
private val dispatcherManager = FakeDispatcherManager()
private val mockDiskSource: ExampleDiskSource = mockk()
private val mockService: ExampleService = mockk()
private val repository = ExampleRepositoryImpl(
clock = fixedClock,
exampleDiskSource = mockDiskSource,
exampleService = mockService,
dispatcherManager = dispatcherManager,
)
@Test
fun `fetchData should return success when service succeeds`() = runTest {
coEvery { mockService.getData(any()) } returns expectedData.asSuccess()
val result = repository.fetchData(userId)
assertTrue(result.isSuccess)
}
}
```
**Key patterns:** Use `FakeDispatcherManager`, fixed Clock, and `.asSuccess()` helpers.
---
## D. Test Data Builders
### Builder Pattern with Number Parameter
**Location:** `network/src/testFixtures/kotlin/com/bitwarden/network/model/`
```kotlin
fun createMockCipher(
number: Int,
id: String = "mockId-$number",
name: String? = "mockName-$number",
// ... more parameters with defaults
): SyncResponseJson.Cipher
// Usage:
val cipher1 = createMockCipher(number = 1) // mockId-1, mockName-1
val cipher2 = createMockCipher(number = 2) // mockId-2, mockName-2
val custom = createMockCipher(number = 3, name = "Custom")
```
**Available Builders (35+):**
- **Cipher:** `createMockCipher()`, `createMockLogin()`, `createMockCard()`, `createMockIdentity()`, `createMockSecureNote()`, `createMockSshKey()`, `createMockField()`, `createMockUri()`, `createMockFido2Credential()`, `createMockPasswordHistory()`, `createMockCipherPermissions()`
- **Sync:** `createMockSyncResponse()`, `createMockFolder()`, `createMockCollection()`, `createMockPolicy()`, `createMockDomains()`
- **Send:** `createMockSend()`, `createMockFile()`, `createMockText()`, `createMockSendJsonRequest()`
- **Profile:** `createMockProfile()`, `createMockOrganization()`, `createMockProvider()`, `createMockPermissions()`
- **Attachments:** `createMockAttachment()`, `createMockAttachmentJsonRequest()`, `createMockAttachmentResponse()`
See `network/src/testFixtures/kotlin/com/bitwarden/network/model/` for full list.
---
## E. Result Type Testing
**Locations:**
- `.asSuccess()`, `.asFailure()`: `core/src/main/kotlin/com/bitwarden/core/data/util/ResultExtensions.kt`
- `assertCoroutineThrows`: `core/src/testFixtures/kotlin/com/bitwarden/core/data/util/TestHelpers.kt`
```kotlin
// Create results
"data".asSuccess() // Result.success("data")
throwable.asFailure() // Result.failure<T>(throwable)
// Assertions
assertTrue(result.isSuccess)
assertEquals(expectedValue, result.getOrNull())
```
---
## F. Test Utilities and Helpers
### Fake Implementations
| Fake | Location | Purpose |
|------|----------|---------|
| `FakeDispatcherManager` | `core/src/testFixtures/` | Deterministic coroutine execution |
| `FakeConfigDiskSource` | `data/src/testFixtures/` | In-memory config storage |
| `FakeSharedPreferences` | `data/src/testFixtures/` | Memory-backed SharedPreferences |
### Exception Testing (CRITICAL)
```kotlin
// CORRECT - Call directly, NOT inside runTest
@Test
fun `test exception`() {
assertCoroutineThrows<IllegalStateException> {
repository.throwingFunction()
}
}
```
**Why:** `runTest` catches exceptions and rethrows them, breaking the assertion pattern.
---
## G. Critical Gotchas
Common testing mistakes in Bitwarden. **For complete details and examples:** See `references/critical-gotchas.md`
**Core Patterns:**
- **assertCoroutineThrows + runTest** - Never wrap in `runTest`; call directly
- **Static mock cleanup** - Always `unmockkStatic()` in `@After`
- **StateFlow vs EventFlow** - StateFlow: `awaitItem()` first; EventFlow: `expectNoEvents()` first
- **FakeDispatcherManager** - Always use instead of real `DispatcherManagerImpl`
- **Coroutine test wrapper** - Use `runTest { }` for all Flow/coroutine tests
**Assertion Patterns:**
- **Complete state assertions** - Assert entire state objects, not individual fields
- **JUnit over Kotlin** - Use `assertTrue()`, not Kotlin's `assert()`
- **Use Result extensions** - Use `asSuccess()` and `asFailure()` for Result type assertions
**Test Design:**
- **Fake vs Mock strategy** - Use Fakes for happy paths, Mocks for error paths
- **DI over static mocking** - Extract interfaces (like UuidManager) instead of mockkStatic
- **Null stream testing** - Test null returns from ContentResolver operations
- **bufferedMutableSharedFlow** - Use with `.onSubscription { emit(state) }` in Fakes
- **Test factory methods** - Accept domain state types, not SavedStateHandle
---
## H. Test File Organization
### Directory Structure
```
module/src/test/kotlin/com/bitwarden/.../
├── ui/*ScreenTest.kt, *ViewModelTest.kt
├── data/repository/*RepositoryTest.kt
└── network/service/*ServiceTest.kt
module/src/testFixtures/kotlin/com/bitwarden/.../
├── util/TestHelpers.kt
├── base/Base*Test.kt
└── model/*Util.kt
```
### Test Naming
- Classes: `*Test.kt`, `*ScreenTest.kt`, `*ViewModelTest.kt`
- Functions: `` `given state when action should result` ``
---
## Summary
Key Bitwarden-specific testing patterns:
1. **BaseViewModelTest** - Automatic dispatcher setup with `stateEventFlow()` helper
2. **BitwardenComposeTest** - Pre-configured with all managers and theme
3. **BaseServiceTest** - MockWebServer setup for network testing
4. **Turbine Flow Testing** - StateFlow (replay) vs EventFlow (no replay)
5. **Test Data Builders** - Consistent `number: Int` parameter pattern
6. **Fake Implementations** - FakeDispatcherManager, FakeConfigDiskSource
7. **Result Type Testing** - `.asSuccess()`, `.asFailure()`
**Always consult:** `docs/ARCHITECTURE.md` and existing test files for reference implementations.
---
## Reference Documentation
For detailed information, see:
- `references/test-base-classes.md` - Detailed base class documentation and usage patterns
- `references/flow-testing-patterns.md` - Complete Turbine patterns for StateFlow/EventFlow
- `references/critical-gotchas.md` - Full anti-pattern reference and debugging tips
**Complete Examples:**
- `examples/viewmodel-test-example.md` - Full ViewModel test with StateFlow/EventFlow
- `examples/compose-screen-test-example.md` - Full Compose screen test
- `examples/repository-test-example.md` - Full repository test with mocks and fakes

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/**
* Complete Compose Screen Test Example
*
* Key patterns demonstrated:
* - Extending BitwardenComposeTest
* - Mocking ViewModel with flows
* - Testing UI interactions
* - Testing navigation callbacks
* - Using bufferedMutableSharedFlow for events
* - Testing dialogs with isDialog() and hasAnyAncestor()
*/
package com.bitwarden.example.feature
import androidx.compose.ui.test.assertIsDisplayed
import androidx.compose.ui.test.filterToOne
import androidx.compose.ui.test.hasAnyAncestor
import androidx.compose.ui.test.isDialog
import androidx.compose.ui.test.onAllNodesWithText
import androidx.compose.ui.test.onNodeWithContentDescription
import androidx.compose.ui.test.onNodeWithText
import androidx.compose.ui.test.performClick
import com.bitwarden.core.data.repository.util.bufferedMutableSharedFlow
import com.bitwarden.ui.util.assertNoDialogExists
import com.bitwarden.ui.util.isProgressBar
import com.x8bit.bitwarden.ui.platform.base.BitwardenComposeTest
import io.mockk.every
import io.mockk.mockk
import io.mockk.verify
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.update
import junit.framework.TestCase.assertTrue
import org.junit.Before
import org.junit.Test
class ExampleScreenTest : BitwardenComposeTest() {
// Track navigation callbacks
private var haveCalledNavigateBack = false
private var haveCalledNavigateToNext = false
// Use bufferedMutableSharedFlow for events (default replay = 0)
private val mutableEventFlow = bufferedMutableSharedFlow<ExampleEvent>()
private val mutableStateFlow = MutableStateFlow(DEFAULT_STATE)
// Mock ViewModel with relaxed = true
private val viewModel = mockk<ExampleViewModel>(relaxed = true) {
every { eventFlow } returns mutableEventFlow
every { stateFlow } returns mutableStateFlow
}
@Before
fun setup() {
haveCalledNavigateBack = false
haveCalledNavigateToNext = false
setContent {
ExampleScreen(
onNavigateBack = { haveCalledNavigateBack = true },
onNavigateToNext = { haveCalledNavigateToNext = true },
viewModel = viewModel,
)
}
}
/**
* Test: Back button sends action to ViewModel
*/
@Test
fun `on back click should send BackClick action`() {
composeTestRule
.onNodeWithContentDescription("Back")
.performClick()
verify { viewModel.trySendAction(ExampleAction.BackClick) }
}
/**
* Test: Submit button sends action to ViewModel
*/
@Test
fun `on submit click should send SubmitClick action`() {
composeTestRule
.onNodeWithText("Submit")
.performClick()
verify { viewModel.trySendAction(ExampleAction.SubmitClick) }
}
/**
* Test: Loading state shows progress indicator
*/
@Test
fun `loading state should display progress indicator`() {
mutableStateFlow.update { it.copy(isLoading = true) }
composeTestRule
.onNode(isProgressBar)
.assertIsDisplayed()
}
/**
* Test: Data state shows content
*/
@Test
fun `data state should display content`() {
mutableStateFlow.update { it.copy(data = "Test Data") }
composeTestRule
.onNodeWithText("Test Data")
.assertIsDisplayed()
}
/**
* Test: Error state shows error message
*/
@Test
fun `error state should display error message`() {
mutableStateFlow.update { it.copy(errorMessage = "Something went wrong") }
composeTestRule
.onNodeWithText("Something went wrong")
.assertIsDisplayed()
}
/**
* Test: NavigateBack event triggers navigation callback
*/
@Test
fun `NavigateBack event should call onNavigateBack`() {
mutableEventFlow.tryEmit(ExampleEvent.NavigateBack)
assertTrue(haveCalledNavigateBack)
}
/**
* Test: NavigateToNext event triggers navigation callback
*/
@Test
fun `NavigateToNext event should call onNavigateToNext`() {
mutableEventFlow.tryEmit(ExampleEvent.NavigateToNext)
assertTrue(haveCalledNavigateToNext)
}
/**
* Test: Item in list can be clicked
*/
@Test
fun `on item click should send ItemClick action`() {
val itemId = "item-123"
mutableStateFlow.update {
it.copy(items = listOf(ExampleItem(id = itemId, name = "Test Item")))
}
composeTestRule
.onNodeWithText("Test Item")
.performClick()
verify { viewModel.trySendAction(ExampleAction.ItemClick(itemId)) }
}
// ==================== DIALOG TESTS ====================
/**
* Test: No dialog exists when dialogState is null
*/
@Test
fun `no dialog should exist when dialogState is null`() {
mutableStateFlow.update { it.copy(dialogState = null) }
composeTestRule.assertNoDialogExists()
}
/**
* Test: Loading dialog displays when state updates
* PATTERN: Use isDialog() to check dialog exists
*/
@Test
fun `loading dialog should display when dialogState is Loading`() {
mutableStateFlow.update {
it.copy(dialogState = ExampleState.DialogState.Loading("Please wait..."))
}
composeTestRule
.onNode(isDialog())
.assertIsDisplayed()
// Verify loading text within dialog using hasAnyAncestor(isDialog())
composeTestRule
.onAllNodesWithText("Please wait...")
.filterToOne(hasAnyAncestor(isDialog()))
.assertIsDisplayed()
}
/**
* Test: Error dialog displays title and message
* PATTERN: Use filterToOne(hasAnyAncestor(isDialog())) to find text within dialogs
*/
@Test
fun `error dialog should display title and message`() {
mutableStateFlow.update {
it.copy(
dialogState = ExampleState.DialogState.Error(
title = "An error has occurred",
message = "Something went wrong. Please try again.",
),
)
}
// Verify dialog exists
composeTestRule
.onNode(isDialog())
.assertIsDisplayed()
// Verify title within dialog
composeTestRule
.onAllNodesWithText("An error has occurred")
.filterToOne(hasAnyAncestor(isDialog()))
.assertIsDisplayed()
// Verify message within dialog
composeTestRule
.onAllNodesWithText("Something went wrong. Please try again.")
.filterToOne(hasAnyAncestor(isDialog()))
.assertIsDisplayed()
}
/**
* Test: Dialog button click sends action
* PATTERN: Find button with hasAnyAncestor(isDialog()) then performClick()
*/
@Test
fun `error dialog dismiss button should send DismissDialog action`() {
mutableStateFlow.update {
it.copy(
dialogState = ExampleState.DialogState.Error(
title = "Error",
message = "An error occurred",
),
)
}
// Click dismiss button within dialog
composeTestRule
.onAllNodesWithText("Ok")
.filterToOne(hasAnyAncestor(isDialog()))
.performClick()
verify { viewModel.trySendAction(ExampleAction.DismissDialog) }
}
/**
* Test: Confirmation dialog with multiple buttons
* PATTERN: Test both confirm and cancel actions
*/
@Test
fun `confirmation dialog confirm button should send ConfirmAction`() {
mutableStateFlow.update {
it.copy(
dialogState = ExampleState.DialogState.Confirmation(
title = "Confirm Action",
message = "Are you sure you want to proceed?",
),
)
}
// Click confirm button
composeTestRule
.onAllNodesWithText("Confirm")
.filterToOne(hasAnyAncestor(isDialog()))
.performClick()
verify { viewModel.trySendAction(ExampleAction.ConfirmAction) }
}
@Test
fun `confirmation dialog cancel button should send DismissDialog action`() {
mutableStateFlow.update {
it.copy(
dialogState = ExampleState.DialogState.Confirmation(
title = "Confirm Action",
message = "Are you sure?",
),
)
}
// Click cancel button
composeTestRule
.onAllNodesWithText("Cancel")
.filterToOne(hasAnyAncestor(isDialog()))
.performClick()
verify { viewModel.trySendAction(ExampleAction.DismissDialog) }
}
}
private val DEFAULT_STATE = ExampleState(
isLoading = false,
data = null,
errorMessage = null,
items = emptyList(),
dialogState = null,
)
// Example types (normally in separate files)
data class ExampleState(
val isLoading: Boolean = false,
val data: String? = null,
val errorMessage: String? = null,
val items: List<ExampleItem> = emptyList(),
val dialogState: DialogState? = null,
) {
/**
* PATTERN: Nested sealed class for dialog states.
* Common dialog types: Loading, Error, Confirmation
*/
sealed class DialogState {
data class Loading(val message: String) : DialogState()
data class Error(val title: String, val message: String) : DialogState()
data class Confirmation(val title: String, val message: String) : DialogState()
}
}
data class ExampleItem(val id: String, val name: String)
sealed class ExampleAction {
data object BackClick : ExampleAction()
data object SubmitClick : ExampleAction()
data class ItemClick(val itemId: String) : ExampleAction()
data object DismissDialog : ExampleAction()
data object ConfirmAction : ExampleAction()
}
sealed class ExampleEvent {
data object NavigateBack : ExampleEvent()
data object NavigateToNext : ExampleEvent()
}

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/**
* Complete Repository Test Example
*
* Key patterns demonstrated:
* - Fake for disk sources, Mock for network services
* - Using FakeDispatcherManager for deterministic coroutines
* - Using fixed Clock for deterministic time
* - Testing Result types with .asSuccess() / .asFailure()
* - Asserting actual objects (not isSuccess/isFailure) for better diagnostics
* - Testing Flow emissions with Turbine
*/
package com.bitwarden.example.data.repository
import app.cash.turbine.test
import com.bitwarden.core.data.manager.dispatcher.FakeDispatcherManager
import com.bitwarden.core.data.repository.util.bufferedMutableSharedFlow
import com.bitwarden.core.data.util.asFailure
import com.bitwarden.core.data.util.asSuccess
import io.mockk.coEvery
import io.mockk.coVerify
import io.mockk.mockk
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.onSubscription
import kotlinx.coroutines.test.runTest
import org.junit.jupiter.api.Assertions.assertEquals
import org.junit.jupiter.api.Assertions.assertNull
import org.junit.jupiter.api.Assertions.assertTrue
import org.junit.jupiter.api.BeforeEach
import org.junit.jupiter.api.Test
import java.time.Clock
import java.time.Instant
import java.time.ZoneOffset
class ExampleRepositoryTest {
// Fixed clock for deterministic time-based tests
private val fixedClock: Clock = Clock.fixed(
Instant.parse("2023-10-27T12:00:00Z"),
ZoneOffset.UTC,
)
// Use FakeDispatcherManager for deterministic coroutine execution
private val dispatcherManager = FakeDispatcherManager()
// Mock service (network layer is always mocked)
private val mockService: ExampleService = mockk()
/**
* PATTERN: Use Fake for disk source in happy path tests.
* This is the Bitwarden convention for repository testing.
*/
private val fakeDiskSource = FakeExampleDiskSource()
private lateinit var repository: ExampleRepositoryImpl
@BeforeEach
fun setup() {
repository = ExampleRepositoryImpl(
clock = fixedClock,
service = mockService,
diskSource = fakeDiskSource,
dispatcherManager = dispatcherManager,
)
}
// ==================== HAPPY PATH TESTS (use Fake) ====================
/**
* Test: Successful fetch returns data and saves to disk
*/
@Test
fun `fetchData should return success and save to disk when service succeeds`() = runTest {
val expectedData = ExampleData(id = "1", name = "Test", updatedAt = fixedClock.instant())
coEvery { mockService.getData() } returns expectedData.asSuccess()
val result = repository.fetchData()
assertEquals(expectedData, result.getOrThrow())
// Fake automatically stores the data - verify it's there
assertEquals(expectedData, fakeDiskSource.storedData)
}
/**
* Test: Service failure returns failure without saving
*/
@Test
fun `fetchData should return failure when service fails`() = runTest {
val exception = Exception("Network error")
coEvery { mockService.getData() } returns exception.asFailure()
val result = repository.fetchData()
assertEquals(exception, result.exceptionOrNull())
// Fake was not updated
assertNull(fakeDiskSource.storedData)
}
/**
* Test: Repository flow emits when disk source updates
*/
@Test
fun `dataFlow should emit when disk source updates`() = runTest {
val data1 = ExampleData(id = "1", name = "First", updatedAt = fixedClock.instant())
val data2 = ExampleData(id = "2", name = "Second", updatedAt = fixedClock.instant())
repository.dataFlow.test {
// Initial null value from Fake
assertNull(awaitItem())
// Update via Fake property setter (triggers emission)
fakeDiskSource.storedData = data1
assertEquals(data1, awaitItem())
// Another update
fakeDiskSource.storedData = data2
assertEquals(data2, awaitItem())
}
}
/**
* Test: Refresh fetches and saves new data
*/
@Test
fun `refresh should fetch new data and update disk source`() = runTest {
val newData = ExampleData(id = "new", name = "Fresh", updatedAt = fixedClock.instant())
coEvery { mockService.getData() } returns newData.asSuccess()
val result = repository.refresh()
assertEquals(Unit, result.getOrThrow())
coVerify { mockService.getData() }
assertEquals(newData, fakeDiskSource.storedData)
}
/**
* Test: Delete clears data from disk
*/
@Test
fun `deleteData should clear disk source`() = runTest {
// Pre-populate the fake
fakeDiskSource.storedData = ExampleData(id = "1", name = "Test", updatedAt = fixedClock.instant())
repository.deleteData()
assertNull(fakeDiskSource.storedData)
}
/**
* Test: Cached data returns from disk when available
*/
@Test
fun `getCachedData should return disk data without network call`() = runTest {
val cachedData = ExampleData(
id = "cached",
name = "Cached",
updatedAt = fixedClock.instant(),
)
fakeDiskSource.storedData = cachedData
val result = repository.getCachedData()
assertEquals(cachedData, result)
coVerify(exactly = 0) { mockService.getData() }
}
// ==================== ERROR PATH TESTS ====================
/**
* PATTERN: For error paths, reconfigure the class-level mock per-test.
* Use coEvery to change mock behavior for each specific test case.
*/
@Test
fun `fetchData should return failure when service returns error`() = runTest {
val exception = Exception("Server unavailable")
coEvery { mockService.getData() } returns exception.asFailure()
val result = repository.fetchData()
assertEquals(exception, result.exceptionOrNull())
// Fake state unchanged on failure
assertNull(fakeDiskSource.storedData)
}
@Test
fun `refresh should return failure and preserve cached data when service fails`() = runTest {
// Pre-populate cache via Fake
val cachedData = ExampleData(id = "cached", name = "Old", updatedAt = fixedClock.instant())
fakeDiskSource.storedData = cachedData
// Reconfigure mock to return failure
coEvery { mockService.getData() } returns Exception("Network error").asFailure()
val result = repository.refresh()
assertTrue(result.isFailure)
// Cached data preserved on failure
assertEquals(cachedData, fakeDiskSource.storedData)
}
}
// Example types (normally in separate files)
data class ExampleData(
val id: String,
val name: String,
val updatedAt: Instant,
)
interface ExampleService {
suspend fun getData(): Result<ExampleData>
}
interface ExampleDiskSource {
val dataFlow: kotlinx.coroutines.flow.Flow<ExampleData?>
fun getData(): ExampleData?
fun saveData(data: ExampleData)
fun clearData()
}
/**
* PATTERN: Fake implementation for happy path testing.
*
* Key characteristics:
* - Uses bufferedMutableSharedFlow(replay = 1) for proper replay behavior
* - Uses .onSubscription { emit(state) } for immediate state emission
* - Private storage with override property setter that emits to flow
* - Test assertions done via the override property getter
*/
class FakeExampleDiskSource : ExampleDiskSource {
private var storedDataValue: ExampleData? = null
private val mutableDataFlow = bufferedMutableSharedFlow<ExampleData?>(replay = 1)
/**
* Override property with getter/setter. Setter emits to flow automatically.
* Tests can read this property for assertions and write to trigger emissions.
*/
var storedData: ExampleData?
get() = storedDataValue
set(value) {
storedDataValue = value
mutableDataFlow.tryEmit(value)
}
override val dataFlow: Flow<ExampleData?>
get() = mutableDataFlow.onSubscription { emit(storedData) }
override fun getData(): ExampleData? = storedData
override fun saveData(data: ExampleData) {
storedData = data
}
override fun clearData() {
storedData = null
}
}

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/**
* Complete ViewModel Test Example
*
* Key patterns demonstrated:
* - Extending BaseViewModelTest
* - Testing StateFlow with Turbine
* - Testing EventFlow with Turbine
* - Using stateEventFlow() for simultaneous testing
* - MockK mocking patterns
* - Test factory method design (accepts domain state, not SavedStateHandle)
* - Complete state assertions (assert entire state objects)
*/
package com.bitwarden.example.feature
import androidx.lifecycle.SavedStateHandle
import app.cash.turbine.test
import com.bitwarden.ui.platform.base.BaseViewModelTest
import io.mockk.coEvery
import io.mockk.coVerify
import io.mockk.every
import io.mockk.mockk
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.test.runTest
import org.junit.jupiter.api.Assertions.assertEquals
import org.junit.jupiter.api.Test
class ExampleViewModelTest : BaseViewModelTest() {
// Mock dependencies
private val mockRepository: ExampleRepository = mockk()
private val mockAuthDiskSource: AuthDiskSource = mockk {
every { userStateFlow } returns MutableStateFlow(null)
}
/**
* StateFlow has replay=1, so first awaitItem() returns current state
*/
@Test
fun `initial state should be default state`() = runTest {
val viewModel = createViewModel()
viewModel.stateFlow.test {
assertEquals(DEFAULT_STATE, awaitItem())
}
}
/**
* Test state transitions: initial -> loading -> success
*/
@Test
fun `LoadData action should update state from idle to loading to success`() = runTest {
val expectedData = "loaded data"
coEvery { mockRepository.fetchData(any()) } returns Result.success(expectedData)
val viewModel = createViewModel()
viewModel.stateFlow.test {
assertEquals(DEFAULT_STATE, awaitItem())
viewModel.trySendAction(ExampleAction.LoadData)
assertEquals(DEFAULT_STATE.copy(isLoading = true), awaitItem())
assertEquals(DEFAULT_STATE.copy(isLoading = false, data = expectedData), awaitItem())
}
coVerify { mockRepository.fetchData(any()) }
}
/**
* EventFlow has no replay - MUST call expectNoEvents() first
*/
@Test
fun `SubmitClick action should emit NavigateToNext event`() = runTest {
coEvery { mockRepository.submitData(any()) } returns Result.success(Unit)
val viewModel = createViewModel()
viewModel.eventFlow.test {
expectNoEvents() // CRITICAL for EventFlow
viewModel.trySendAction(ExampleAction.SubmitClick)
assertEquals(ExampleEvent.NavigateToNext, awaitItem())
}
}
/**
* Use stateEventFlow() helper for simultaneous testing
*/
@Test
fun `complex action should update state and emit event`() = runTest {
coEvery { mockRepository.complexOperation(any()) } returns Result.success("result")
val viewModel = createViewModel()
viewModel.stateEventFlow(backgroundScope) { stateFlow, eventFlow ->
assertEquals(DEFAULT_STATE, stateFlow.awaitItem())
eventFlow.expectNoEvents()
viewModel.trySendAction(ExampleAction.ComplexAction)
assertEquals(DEFAULT_STATE.copy(isLoading = true), stateFlow.awaitItem())
assertEquals(DEFAULT_STATE.copy(data = "result"), stateFlow.awaitItem())
assertEquals(ExampleEvent.ShowToast("Success!"), eventFlow.awaitItem())
}
}
/**
* Test state restoration from saved state.
* Note: Use initialState parameter, NOT SavedStateHandle directly.
*/
@Test
fun `initial state from saved state should be preserved`() = runTest {
// Build complete expected state - always assert full objects
val savedState = ExampleState(
isLoading = false,
data = "restored data",
errorMessage = null,
)
val viewModel = createViewModel(initialState = savedState)
viewModel.stateFlow.test {
assertEquals(savedState, awaitItem())
}
}
/**
* Factory method accepts domain state, NOT SavedStateHandle.
* This hides Android framework details from test logic.
*/
private fun createViewModel(
initialState: ExampleState? = null,
): ExampleViewModel = ExampleViewModel(
savedStateHandle = SavedStateHandle().apply { set("state", initialState) },
repository = mockRepository,
authDiskSource = mockAuthDiskSource,
)
}
private val DEFAULT_STATE = ExampleState(
isLoading = false,
data = null,
errorMessage = null,
)
// Example types (normally in separate files)
data class ExampleState(
val isLoading: Boolean = false,
val data: String? = null,
val errorMessage: String? = null,
)
sealed class ExampleAction {
data object LoadData : ExampleAction()
data object SubmitClick : ExampleAction()
data object ComplexAction : ExampleAction()
}
sealed class ExampleEvent {
data object NavigateToNext : ExampleEvent()
data class ShowToast(val message: String) : ExampleEvent()
}

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# Critical Gotchas and Anti-Patterns
Common mistakes and pitfalls when writing tests in the Bitwarden Android codebase.
## ❌ NEVER wrap assertCoroutineThrows in runTest
### The Problem
`runTest` catches exceptions and rethrows them, which breaks the `assertCoroutineThrows` assertion pattern.
### Wrong
```kotlin
@Test
fun `test exception`() = runTest {
assertCoroutineThrows<Exception> {
repository.throwingFunction()
} // Won't work - exception is caught by runTest!
}
```
### Correct
```kotlin
@Test
fun `test exception`() {
assertCoroutineThrows<Exception> {
repository.throwingFunction()
} // Works correctly
}
```
### Why This Happens
`runTest` provides a coroutine scope and catches exceptions to provide better error messages. However, `assertCoroutineThrows` needs to catch the exception itself to verify it was thrown. When wrapped in `runTest`, the exception is caught twice, breaking the assertion.
## ❌ ALWAYS unmock static functions
### The Problem
MockK's static mocking persists across tests. Forgetting to clean up causes mysterious failures in subsequent tests.
### Wrong
```kotlin
@Before
fun setup() {
mockkStatic(::isBuildVersionAtLeast)
every { isBuildVersionAtLeast(any()) } returns true
}
// Forgot @After - subsequent tests will fail mysteriously!
```
### Correct
```kotlin
@Before
fun setup() {
mockkStatic(::isBuildVersionAtLeast)
every { isBuildVersionAtLeast(any()) } returns true
}
@After
fun tearDown() {
unmockkStatic(::isBuildVersionAtLeast) // CRITICAL
}
```
### Common Static Functions to Watch
```kotlin
// Platform version checks
mockkStatic(::isBuildVersionAtLeast)
unmockkStatic(::isBuildVersionAtLeast)
// URI parsing
mockkStatic(Uri::class)
unmockkStatic(Uri::class)
// Static utility functions
mockkStatic(MyUtilClass::class)
unmockkStatic(MyUtilClass::class)
```
### Debugging Tip
If tests pass individually but fail when run together, suspect static mocking cleanup issues.
## ❌ Don't confuse StateFlow and EventFlow testing
### StateFlow (replay = 1)
```kotlin
// CORRECT - StateFlow always has current value
viewModel.stateFlow.test {
val initial = awaitItem() // Gets current state immediately
viewModel.trySendAction(action)
val updated = awaitItem() // Gets new state
}
```
### EventFlow (no replay)
```kotlin
// CORRECT - EventFlow has no initial value
viewModel.eventFlow.test {
expectNoEvents() // MUST do this first
viewModel.trySendAction(action)
val event = awaitItem() // Gets emitted event
}
```
### Common Mistake
```kotlin
// WRONG - Forgetting expectNoEvents() on EventFlow
viewModel.eventFlow.test {
viewModel.trySendAction(action) // May cause flaky tests
assertEquals(event, awaitItem())
}
```
## ❌ Don't mix real and test dispatchers
### Wrong
```kotlin
private val repository = ExampleRepositoryImpl(
dispatcherManager = DispatcherManagerImpl(), // Real dispatcher!
)
@Test
fun `test repository`() = runTest {
// Test will have timing issues - real dispatcher != test dispatcher
}
```
### Correct
```kotlin
private val repository = ExampleRepositoryImpl(
dispatcherManager = FakeDispatcherManager(), // Test dispatcher
)
@Test
fun `test repository`() = runTest {
// Test runs deterministically
}
```
### Why This Matters
Real dispatchers use actual thread pools and delays. Test dispatchers (UnconfinedTestDispatcher) execute immediately and deterministically. Mixing them causes:
- Non-deterministic test failures
- Real delays in tests (slow test suite)
- Race conditions
### Always Use
- `FakeDispatcherManager()` for repositories
- `UnconfinedTestDispatcher()` when manually creating dispatchers
- `runTest` for coroutine tests (provides TestDispatcher automatically)
## ❌ Don't forget to use runTest for coroutine tests
### Wrong
```kotlin
@Test
fun `test coroutine`() {
viewModel.stateFlow.test { /* ... */ } // Missing runTest!
}
```
This causes:
- Test completes before coroutines finish
- False positives (test passes but assertions never run)
- Mysterious failures
### Correct
```kotlin
@Test
fun `test coroutine`() = runTest {
viewModel.stateFlow.test { /* ... */ }
}
```
### When runTest is Required
- Testing ViewModels (they use `viewModelScope`)
- Testing Flows with Turbine `.test {}`
- Testing repositories with suspend functions
- Any test calling suspend functions
### Exception: assertCoroutineThrows
As noted above, `assertCoroutineThrows` should NOT be wrapped in `runTest`.
## ❌ Don't forget relaxed = true for complex mocks
### Without relaxed
```kotlin
private val viewModel = mockk<ExampleViewModel>() // Must mock every method!
// Error: "no answer found for: stateFlow"
```
### With relaxed
```kotlin
private val viewModel = mockk<ExampleViewModel>(relaxed = true) {
// Only mock what you care about
every { stateFlow } returns mutableStateFlow
every { eventFlow } returns mutableEventFlow
}
```
### When to Use relaxed
- Mocking ViewModels in Compose tests
- Mocking complex objects with many methods
- When you only care about specific method calls
### When NOT to Use relaxed
- Mocking repository interfaces (be explicit about behavior)
- When you want to verify NO unexpected calls
- Testing error paths (want test to fail if unexpected method called)
## ❌ Don't assert individual fields when complete state is available
### The Problem
Asserting individual state fields can miss unintended side effects on other fields.
### Wrong
```kotlin
@Test
fun `action should update state`() = runTest {
viewModel.trySendAction(SomeAction.DoThing)
val state = viewModel.stateFlow.value
assertEquals(null, state.dialog) // Only checks one field!
}
```
### Correct
```kotlin
@Test
fun `action should update state`() = runTest {
viewModel.trySendAction(SomeAction.DoThing)
val expected = SomeState(
isLoading = false,
data = "result",
dialog = null,
)
assertEquals(expected, viewModel.stateFlow.value) // Checks all fields
}
```
### Why This Matters
- Catches unintended mutations to other state fields
- Makes expected state explicit and readable
- Prevents silent regressions when state structure changes
---
## ❌ Don't use Kotlin assert() for boolean checks
### The Problem
Kotlin's `assert()` doesn't follow JUnit conventions and provides poor failure messages.
### Wrong
```kotlin
@Test
fun `event should trigger callback`() {
mutableEventFlow.tryEmit(SomeEvent.Navigate)
assert(onNavigateCalled) // Kotlin assert - bad failure messages
}
```
### Correct
```kotlin
@Test
fun `event should trigger callback`() {
mutableEventFlow.tryEmit(SomeEvent.Navigate)
assertTrue(onNavigateCalled) // JUnit assertTrue - proper assertion
}
```
### Always Use JUnit Assertions
- `assertTrue()` / `assertFalse()` for booleans
- `assertEquals()` for value comparisons
- `assertNotNull()` / `assertNull()` for nullability
- `assertThrows<T>()` for exceptions
---
## ❌ Don't pass SavedStateHandle to test factory methods
### The Problem
Exposing `SavedStateHandle` in test factory methods leaks Android framework details into test logic.
### Wrong
```kotlin
private fun createViewModel(
savedStateHandle: SavedStateHandle = SavedStateHandle(), // Framework type exposed
): MyViewModel = MyViewModel(
savedStateHandle = savedStateHandle,
repository = mockRepository,
)
@Test
fun `initial state from saved state`() = runTest {
val savedState = MyState(isLoading = true)
val savedStateHandle = SavedStateHandle(mapOf("state" to savedState))
val viewModel = createViewModel(savedStateHandle = savedStateHandle)
// ...
}
```
### Correct
```kotlin
private fun createViewModel(
initialState: MyState? = null, // Domain type only
): MyViewModel = MyViewModel(
savedStateHandle = SavedStateHandle().apply { set("state", initialState) },
repository = mockRepository,
)
@Test
fun `initial state from saved state`() = runTest {
val savedState = MyState(isLoading = true)
val viewModel = createViewModel(initialState = savedState)
// ...
}
```
### Why This Matters
- Cleaner, more intuitive test code
- Hides SavedStateHandle implementation details
- Follows Bitwarden conventions
---
## ❌ Don't test SavedStateHandle persistence in unit tests
### The Problem
Testing whether state persists to SavedStateHandle is testing Android framework behavior, not your business logic.
### Wrong
```kotlin
@Test
fun `state should persist to SavedStateHandle`() = runTest {
val savedStateHandle = SavedStateHandle()
val viewModel = createViewModel(savedStateHandle = savedStateHandle)
viewModel.trySendAction(SomeAction)
val savedState = savedStateHandle.get<MyState>("state")
assertEquals(expectedState, savedState) // Testing framework, not logic!
}
```
### Correct
Focus on testing business logic and state transformations:
```kotlin
@Test
fun `action should update state correctly`() = runTest {
val viewModel = createViewModel()
viewModel.trySendAction(SomeAction)
assertEquals(expectedState, viewModel.stateFlow.value) // Test observable state
}
```
---
## ❌ Don't use static mocking when DI pattern is available
### The Problem
Static mocking (`mockkStatic`) is harder to maintain and less testable than dependency injection.
### Wrong
```kotlin
class ParserTest {
@BeforeEach
fun setup() {
mockkStatic(UUID::class)
every { UUID.randomUUID() } returns mockk {
every { toString() } returns "fixed-uuid"
}
}
@AfterEach
fun tearDown() {
unmockkStatic(UUID::class)
}
}
```
### Correct
Extract an interface and inject it:
```kotlin
// Production code
interface UuidManager {
fun generateUuid(): String
}
class UuidManagerImpl : UuidManager {
override fun generateUuid(): String = UUID.randomUUID().toString()
}
class Parser(private val uuidManager: UuidManager) { ... }
// Test code
class ParserTest {
private val mockUuidManager = mockk<UuidManager>()
@BeforeEach
fun setup() {
every { mockUuidManager.generateUuid() } returns "fixed-uuid"
}
// No tearDown needed - no static mocking!
}
```
### When to Use This Pattern
- UUID generation
- Timestamp/Clock operations
- System property access
- Any static function that needs deterministic testing
---
## ❌ Don't forget to test null stream returns from Android APIs
### The Problem
Android's `ContentResolver.openOutputStream()` and `openInputStream()` can return null, not just throw exceptions.
### Wrong
```kotlin
class FileManagerTest {
@Test
fun `stringToUri with exception should return false`() = runTest {
every { mockContentResolver.openOutputStream(any()) } throws IOException()
val result = fileManager.stringToUri(mockUri, "data")
assertFalse(result)
}
// Missing: test for null return!
}
```
### Correct
```kotlin
class FileManagerTest {
@Test
fun `stringToUri with exception should return false`() = runTest {
every { mockContentResolver.openOutputStream(any()) } throws IOException()
val result = fileManager.stringToUri(mockUri, "data")
assertFalse(result)
}
@Test
fun `stringToUri with null stream should return false`() = runTest {
every { mockContentResolver.openOutputStream(any()) } returns null
val result = fileManager.stringToUri(mockUri, "data")
assertFalse(result) // CRITICAL: must handle null!
}
}
```
### Common Android APIs That Return Null
- `ContentResolver.openOutputStream()` / `openInputStream()`
- `Context.getExternalFilesDir()`
- `PackageManager.getApplicationInfo()` (can throw)
---
## Bitwarden Mocking Guidelines
**Mock at architectural boundaries:**
- Repository → ViewModel (mock repository)
- Service → Repository (mock service)
- API → Service (use MockWebServer, not mocks)
- DiskSource → Repository (mock disk source)
**Fake vs Mock Strategy (IMPORTANT):**
- **Happy paths**: Use Fake implementations (`FakeAuthenticatorDiskSource`, `FakeVaultDiskSource`)
- **Error paths**: Use MockK with isolated repository instances
```kotlin
// Happy path - use Fake
private val fakeDiskSource = FakeAuthenticatorDiskSource()
@Test
fun `createItem should return Success`() = runTest {
val result = repository.createItem(mockItem)
assertEquals(CreateItemResult.Success, result)
}
// Error path - use isolated Mock
@Test
fun `createItem with exception should return Error`() = runTest {
val mockDiskSource = mockk<AuthenticatorDiskSource> {
coEvery { saveItem(any()) } throws RuntimeException()
}
val repository = RepositoryImpl(diskSource = mockDiskSource)
val result = repository.createItem(mockItem)
assertEquals(CreateItemResult.Error, result)
}
```
**Use Fakes for:**
- `FakeDispatcherManager` - deterministic coroutines
- `FakeConfigDiskSource` - in-memory config storage
- `FakeSharedPreferences` - memory-backed preferences
- `FakeAuthenticatorDiskSource` - in-memory authenticator storage
**Create real instances for:**
- Data classes, value objects (User, Config, CipherView)
- Test data builders (`createMockCipher(number = 1)`)
## ❌ Don't forget bufferedMutableSharedFlow with onSubscription for Fakes
### The Problem
Fake data sources using `MutableSharedFlow` won't emit cached state to new subscribers without explicit handling.
### Wrong
```kotlin
class FakeDataSource : DataSource {
private val mutableFlow = MutableSharedFlow<List<Item>>()
private val storedItems = mutableListOf<Item>()
override fun getItems(): Flow<List<Item>> = mutableFlow
override suspend fun saveItem(item: Item) {
storedItems.add(item)
mutableFlow.emit(storedItems)
}
}
// Test: Initial collection gets nothing!
repository.dataFlow.test {
// Hangs or fails - no initial emission
}
```
### Correct
```kotlin
class FakeDataSource : DataSource {
private val mutableFlow = bufferedMutableSharedFlow<List<Item>>()
private val storedItems = mutableListOf<Item>()
override fun getItems(): Flow<List<Item>> = mutableFlow
.onSubscription { emit(storedItems.toList()) }
override suspend fun saveItem(item: Item) {
storedItems.add(item)
mutableFlow.emit(storedItems.toList())
}
}
// Test: Initial collection receives current state
repository.dataFlow.test {
assertEquals(emptyList(), awaitItem()) // Works!
}
```
### Key Points
- Use `bufferedMutableSharedFlow()` from `core/data/repository/util/`
- Add `.onSubscription { emit(currentState) }` for immediate state emission
- This ensures new collectors receive the current cached state
---
## ✅ Use Result extension functions for assertions
### The Pattern
Use `asSuccess()` and `asFailure()` extensions from `com.bitwarden.core.data.util` for cleaner Result assertions.
### Success Path
```kotlin
@Test
fun `getData should return success`() = runTest {
val result = repository.getData()
val expected = expectedData.asSuccess()
assertEquals(expected.getOrNull(), result.getOrNull())
}
```
### Failure Path
```kotlin
@Test
fun `getData with error should return failure`() = runTest {
val exception = IOException("Network error")
coEvery { mockService.getData() } returns exception.asFailure()
val result = repository.getData()
assertTrue(result.isFailure)
assertEquals(exception, result.exceptionOrNull())
}
```
### Avoid Redundant Assertions
```kotlin
// WRONG - redundant success checks
assertTrue(result.isSuccess)
assertTrue(expected.isSuccess)
assertArrayEquals(expected.getOrNull(), result.getOrNull())
// CORRECT - final assertion is sufficient
assertArrayEquals(expected.getOrNull(), result.getOrNull())
```
---
## Summary Checklist
Before submitting tests, verify:
**Core Patterns:**
- [ ] No `assertCoroutineThrows` inside `runTest`
- [ ] All static mocks have `unmockk` in `@After`
- [ ] EventFlow tests start with `expectNoEvents()`
- [ ] Using FakeDispatcherManager, not real dispatchers
- [ ] All coroutine tests use `runTest`
**Assertion Patterns:**
- [ ] Assert complete state objects, not individual fields
- [ ] Use JUnit `assertTrue()`, not Kotlin `assert()`
- [ ] Use `asSuccess()` for Result type assertions
- [ ] Avoid redundant assertion patterns
**Test Design:**
- [ ] Test factory methods accept domain types, not SavedStateHandle
- [ ] Use Fakes for happy paths, Mocks for error paths
- [ ] Prefer DI patterns over static mocking
- [ ] Test null returns from Android APIs (streams, files)
- [ ] Fakes use `bufferedMutableSharedFlow()` with `.onSubscription`
**General:**
- [ ] Tests don't depend on execution order
- [ ] Complex mocks use `relaxed = true`
- [ ] Test data is created fresh for each test
- [ ] Mocking behavior, not value objects
- [ ] Testing observable behavior, not implementation
When tests fail mysteriously, check these gotchas first.

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# Flow Testing with Turbine
Bitwarden Android uses Turbine for testing Kotlin Flows, including the critical distinction between StateFlow and EventFlow patterns.
## StateFlow vs EventFlow
### StateFlow (Replayed)
**Characteristics:**
- `replay = 1` - Always emits current value to new collectors
- First `awaitItem()` returns the current/initial state
- Survives configuration changes
- Used for UI state that needs to be immediately available
**Test Pattern:**
```kotlin
@Test
fun `action should update state`() = runTest {
val viewModel = MyViewModel(savedStateHandle, mockRepository)
viewModel.stateFlow.test {
// First awaitItem() gets CURRENT state
assertEquals(INITIAL_STATE, awaitItem())
// Trigger action
viewModel.trySendAction(MyAction.LoadData)
// Next awaitItem() gets UPDATED state
assertEquals(LOADING_STATE, awaitItem())
assertEquals(SUCCESS_STATE, awaitItem())
}
}
```
### EventFlow (No Replay)
**Characteristics:**
- `replay = 0` - Only emits new events after subscription
- No initial value emission
- One-time events (navigation, toasts, dialogs)
- Does not survive configuration changes
**Test Pattern:**
```kotlin
@Test
fun `action should emit event`() = runTest {
val viewModel = MyViewModel(savedStateHandle, mockRepository)
viewModel.eventFlow.test {
// MUST call expectNoEvents() first - nothing emitted yet
expectNoEvents()
// Trigger action
viewModel.trySendAction(MyAction.Submit)
// Now expect the event
assertEquals(MyEvent.NavigateToNext, awaitItem())
}
}
```
**Critical:** Always call `expectNoEvents()` before triggering actions on EventFlow. Forgetting this causes flaky tests.
## Testing State and Events Simultaneously
Use the `stateEventFlow()` helper from `BaseViewModelTest`:
```kotlin
@Test
fun `complex action should update state and emit event`() = runTest {
val viewModel = MyViewModel(savedStateHandle, mockRepository)
viewModel.stateEventFlow(backgroundScope) { stateFlow, eventFlow ->
// Initial state
assertEquals(INITIAL_STATE, stateFlow.awaitItem())
// No events yet
eventFlow.expectNoEvents()
// Trigger action
viewModel.trySendAction(MyAction.ComplexAction)
// Verify state progression
assertEquals(LOADING_STATE, stateFlow.awaitItem())
assertEquals(SUCCESS_STATE, stateFlow.awaitItem())
// Verify event emission
assertEquals(MyEvent.ShowToast, eventFlow.awaitItem())
}
}
```
## Repository Flow Testing
### Testing Database Flows
```kotlin
@Test
fun `dataFlow should emit when database updates`() = runTest {
val dataFlow = MutableStateFlow(initialData)
every { mockDiskSource.dataFlow } returns dataFlow
repository.dataFlow.test {
// Initial value
assertEquals(initialData, awaitItem())
// Update disk source
dataFlow.value = updatedData
// Verify emission
assertEquals(updatedData, awaitItem())
}
}
```
### Testing Transformed Flows
```kotlin
@Test
fun `flow transformation should map correctly`() = runTest {
val sourceFlow = MutableStateFlow(UserEntity(id = "1", name = "John"))
every { mockDao.observeUser() } returns sourceFlow
// Repository transforms entity to domain model
repository.userFlow.test {
val expectedUser = User(id = "1", name = "John")
assertEquals(expectedUser, awaitItem())
}
}
```
## Common Patterns
### Pattern 1: Testing Initial State + Action
```kotlin
@Test
fun `load data should update from idle to loading to success`() = runTest {
coEvery { repository.getData() } returns "data".asSuccess()
viewModel.stateFlow.test {
assertEquals(DEFAULT_STATE, awaitItem())
viewModel.loadData()
assertEquals(DEFAULT_STATE.copy(loadingState = LoadingState.Loading), awaitItem())
assertEquals(DEFAULT_STATE.copy(loadingState = LoadingState.Success), awaitItem())
}
}
```
### Pattern 2: Testing Error States
```kotlin
@Test
fun `load data with error should emit failure state`() = runTest {
val error = Exception("Network error")
coEvery { repository.getData() } returns error.asFailure()
viewModel.stateFlow.test {
assertEquals(DEFAULT_STATE, awaitItem())
viewModel.loadData()
assertEquals(DEFAULT_STATE.copy(loadingState = LoadingState.Loading), awaitItem())
assertEquals(
DEFAULT_STATE.copy(loadingState = LoadingState.Error("Network error")),
awaitItem(),
)
}
}
```
### Pattern 3: Testing Event Sequences
```kotlin
@Test
fun `submit should emit validation then navigation events`() = runTest {
viewModel.eventFlow.test {
expectNoEvents()
viewModel.trySendAction(MyAction.Submit)
assertEquals(MyEvent.ShowValidation, awaitItem())
assertEquals(MyEvent.NavigateToNext, awaitItem())
}
}
```
### Pattern 4: Testing Cancellation
```kotlin
@Test
fun `cancelling collection should stop emissions`() = runTest {
val flow = flow {
repeat(100) {
emit(it)
delay(100)
}
}
flow.test {
assertEquals(0, awaitItem())
assertEquals(1, awaitItem())
// Cancel after 2 items
cancel()
// No more items received
}
}
```
## Anti-Patterns
### ❌ Forgetting expectNoEvents() on EventFlow
```kotlin
// WRONG
viewModel.eventFlow.test {
viewModel.trySendAction(action) // May fail - no initial expectNoEvents
assertEquals(event, awaitItem())
}
// CORRECT
viewModel.eventFlow.test {
expectNoEvents() // ALWAYS do this first
viewModel.trySendAction(action)
assertEquals(event, awaitItem())
}
```
### ❌ Not Using runTest
```kotlin
// WRONG - Missing runTest
@Test
fun `test flow`() {
flow.test { /* ... */ }
}
// CORRECT
@Test
fun `test flow`() = runTest {
flow.test { /* ... */ }
}
```
### ❌ Mixing StateFlow and EventFlow Patterns
```kotlin
// WRONG - Treating StateFlow like EventFlow
stateFlow.test {
expectNoEvents() // Unnecessary - StateFlow always has value
/* ... */
}
// WRONG - Treating EventFlow like StateFlow
eventFlow.test {
val item = awaitItem() // Will hang - no initial value!
/* ... */
}
```
## Reference Implementations
**ViewModel with StateFlow and EventFlow:**
`app/src/test/kotlin/com/x8bit/bitwarden/ui/tools/feature/generator/GeneratorViewModelTest.kt`
**Repository Flow Testing:**
`data/src/test/kotlin/com/bitwarden/data/tools/generator/repository/GeneratorRepositoryTest.kt`
**Complex Flow Transformations:**
`data/src/test/kotlin/com/bitwarden/data/vault/repository/VaultRepositoryTest.kt`

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# Test Base Classes Reference
Bitwarden Android provides specialized base classes that configure test environments and provide helper utilities.
## BaseViewModelTest
**Location:** `ui/src/testFixtures/kotlin/com/bitwarden/ui/platform/base/BaseViewModelTest.kt`
### Purpose
Provides essential setup for testing ViewModels with proper coroutine dispatcher configuration and Flow testing helpers.
### Automatic Configuration
- Registers `MainDispatcherExtension` for `UnconfinedTestDispatcher`
- Ensures deterministic coroutine execution in tests
- All coroutines complete immediately without real delays
### Key Feature: stateEventFlow() Helper
**Use Case:** When you need to test both StateFlow and EventFlow simultaneously.
```kotlin
@Test
fun `complex action should update state and emit event`() = runTest {
val viewModel = ExampleViewModel(savedStateHandle, mockRepository)
viewModel.stateEventFlow(backgroundScope) { stateFlow, eventFlow ->
// Verify initial state
assertEquals(INITIAL_STATE, stateFlow.awaitItem())
// No events yet
eventFlow.expectNoEvents()
// Trigger action
viewModel.trySendAction(ExampleAction.ComplexAction)
// Verify state updated
assertEquals(LOADING_STATE, stateFlow.awaitItem())
// Verify event emitted
assertEquals(ExampleEvent.ShowToast, eventFlow.awaitItem())
}
}
```
### Usage Pattern
```kotlin
class MyViewModelTest : BaseViewModelTest() {
private val mockRepository: MyRepository = mockk()
private val savedStateHandle = SavedStateHandle(
mapOf(KEY_STATE to INITIAL_STATE)
)
@Test
fun `test action`() = runTest {
val viewModel = MyViewModel(
savedStateHandle = savedStateHandle,
repository = mockRepository
)
// Test with automatic dispatcher setup
viewModel.stateFlow.test {
assertEquals(INITIAL_STATE, awaitItem())
}
}
}
```
## BitwardenComposeTest
**Location:** `app/src/test/kotlin/com/x8bit/bitwarden/ui/platform/base/BitwardenComposeTest.kt`
### Purpose
Pre-configured test class for Compose UI tests with all Bitwarden managers and theme setup.
### Automatic Configuration
- All Bitwarden managers pre-configured (FeatureFlags, AuthTab, Biometrics, etc.)
- Wraps content in `BitwardenTheme` and `LocalManagerProvider`
- Provides fixed `Clock` for deterministic time-based tests
- Extends `BaseComposeTest` for Robolectric and dispatcher setup
### Key Features
**Pre-configured Managers:**
- `FeatureFlagManager` - Controls feature flag behavior
- `AuthTabManager` - Manages auth tab state
- `BiometricsManager` - Handles biometric authentication
- `ClipboardManager` - Clipboard operations
- `NotificationManager` - Notification display
**Fixed Clock:**
All tests use a fixed clock for deterministic time-based testing:
```kotlin
// Tests use consistent time: 2023-10-27T12:00:00Z
val fixedClock: Clock
```
### Usage Pattern
```kotlin
class MyScreenTest : BitwardenComposeTest() {
private var haveCalledNavigateBack = false
private val mutableEventFlow = bufferedMutableSharedFlow<MyEvent>()
private val mutableStateFlow = MutableStateFlow(DEFAULT_STATE)
private val viewModel = mockk<MyViewModel>(relaxed = true) {
every { eventFlow } returns mutableEventFlow
every { stateFlow } returns mutableStateFlow
}
@Before
fun setup() {
setContent {
MyScreen(
onNavigateBack = { haveCalledNavigateBack = true },
viewModel = viewModel
)
}
}
@Test
fun `on back click should send action`() {
composeTestRule.onNodeWithContentDescription("Back").performClick()
verify { viewModel.trySendAction(MyAction.BackClick) }
}
@Test
fun `loading state should show progress`() {
mutableStateFlow.value = DEFAULT_STATE.copy(isLoading = true)
composeTestRule.onNode(isProgressBar).assertIsDisplayed()
}
}
```
### Important: bufferedMutableSharedFlow for Events
In Compose tests, use `bufferedMutableSharedFlow` instead of regular `MutableSharedFlow` (default replay is 0):
```kotlin
// Correct for Compose tests
private val mutableEventFlow = bufferedMutableSharedFlow<MyEvent>()
// This allows triggering events and having the UI react
mutableEventFlow.tryEmit(MyEvent.NavigateBack)
```
## BaseServiceTest
**Location:** `network/src/testFixtures/kotlin/com/bitwarden/network/base/BaseServiceTest.kt`
### Purpose
Provides MockWebServer setup for testing API service implementations.
### Automatic Configuration
- `server: MockWebServer` - Auto-started before each test, stopped after
- `retrofit: Retrofit` - Pre-configured with:
- JSON converter (kotlinx.serialization)
- NetworkResultCallAdapter for Result<T> responses
- Base URL pointing to MockWebServer
- `json: Json` - kotlinx.serialization JSON instance
### Usage Pattern
```kotlin
class MyServiceTest : BaseServiceTest() {
private val api: MyApi = retrofit.create()
private val service = MyServiceImpl(api)
@Test
fun `getConfig should return success when API succeeds`() = runTest {
// Enqueue mock response
server.enqueue(MockResponse().setBody(EXPECTED_JSON))
// Call service
val result = service.getConfig()
// Verify result
assertEquals(EXPECTED_RESPONSE.asSuccess(), result)
}
@Test
fun `getConfig should return failure when API fails`() = runTest {
// Enqueue error response
server.enqueue(MockResponse().setResponseCode(500))
// Call service
val result = service.getConfig()
// Verify failure
assertTrue(result.isFailure)
}
}
```
### MockWebServer Patterns
**Enqueue successful response:**
```kotlin
server.enqueue(MockResponse().setBody("""{"key": "value"}"""))
```
**Enqueue error response:**
```kotlin
server.enqueue(MockResponse().setResponseCode(404))
server.enqueue(MockResponse().setResponseCode(500))
```
**Enqueue delayed response:**
```kotlin
server.enqueue(
MockResponse()
.setBody("""{"key": "value"}""")
.setBodyDelay(1000, TimeUnit.MILLISECONDS)
)
```
**Verify request details:**
```kotlin
val request = server.takeRequest()
assertEquals("/api/config", request.path)
assertEquals("GET", request.method)
assertEquals("Bearer token", request.getHeader("Authorization"))
```
## BaseComposeTest
**Location:** `ui/src/testFixtures/kotlin/com/bitwarden/ui/platform/base/BaseComposeTest.kt`
### Purpose
Base class for Compose tests that extends `BaseRobolectricTest` and provides `setTestContent()` helper.
### Features
- Robolectric configuration for Compose
- Proper dispatcher setup
- `composeTestRule` for UI testing
- `setTestContent()` helper wraps content in theme
### Usage
Typically you'll extend `BitwardenComposeTest` which extends this class. Use `BaseComposeTest` directly only for tests that don't need Bitwarden-specific manager configuration.
## When to Use Each Base Class
| Test Type | Base Class | Use When |
|-----------|------------|----------|
| ViewModel tests | `BaseViewModelTest` | Testing ViewModel state and events |
| Compose screen tests | `BitwardenComposeTest` | Testing Compose UI with Bitwarden components |
| API service tests | `BaseServiceTest` | Testing network layer with MockWebServer |
| Repository tests | None (manual setup) | Testing repository logic with mocked dependencies |
| Utility/helper tests | None (manual setup) | Testing pure functions or utilities |
## Complete Examples
**ViewModel Test:**
`../examples/viewmodel-test-example.md`
**Compose Screen Test:**
`../examples/compose-screen-test-example.md`
**Repository Test:**
`../examples/repository-test-example.md`