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Method isDigitsOnly in android.text.TextUtils not mocked Error

I created a validation use case in which I'm validating the input using isDigitsOnly that use TextUtils internally.
override fun isDigitsOnly(size: String): Boolean {
return !size.trim().isDigitsOnly()
}
when I tried to test it, I got this error
Method isDigitsOnly in android.text.TextUtils not mocked
Does anyone know how I can mock the textUtils in my test class
#RunWith(MockitoJUnitRunner::class)
class ValidationInputImplTest {
#Mock
private lateinit var mMockTextUtils: TextUtils
private lateinit var validationInputImpl: ValidationInputImpl
#Before
fun setUp() {
validationInputImpl = ValidationInputImpl()
}
#Test
fun `contains only digits, returns success`() {
val input = "66"
val result = validationInputImpl(input)
assertTrue(result is ValidationResult.Success)
}
}

At the time of writing the answer,you cannot do that. Because the android code ,that you see is not actual code. You cannot create unit test for that. The default implementation of the methods in android.jar is to throw exception.
One thing you can do is, adding the below in build.gradle file.
But it make the android classes not to throw exception. But it will always return default value. So the test result may actually not work. It is strictly not recommended.
android {
testOptions {
unitTests.returnDefaultValues = true
}
}
The better way to do copy the code from android source and paste the file under src/test/java folder with package name as android.text .
Link to Answer

Android instrumented test freezes when it tests a suspend function that uses RoomDatabase.withTransaction

I'm trying to test the following LocalDataSource function, NameLocalData.methodThatFreezes function, but it freezes. How can I solve this? Or How can I test it in another way?
Class to be tested
class NameLocalData(private val roomDatabase: RoomDatabase) : NameLocalDataSource {
override suspend fun methodThatFreezes(someParameter: Something): Something {
roomDatabase.withTransaction {
try {
// calling room DAO methods here
} catch(e: SQLiteConstraintException) {
// ...
}
return something
}
}
}
Test class
#MediumTest
#RunWith(AndroidJUnit4::class)
class NameLocalDataTest {
private lateinit var nameLocalData: NameLocalData
// creates a Room database in memory
#get:Rule
var roomDatabaseRule = RoomDatabaseRule()
#get:Rule
var instantTaskExecutorRule = InstantTaskExecutorRule()
#Before
fun setup() = runBlockingTest {
initializesSomeData()
nameLocalData = NameLocalData(roomDatabaseRule.db)
}
#Test
fun methodThatFreezes() = runBlockingTest {
nameLocalData.methodThatFreezes // test freezes
}
// ... others NameLocalDataTest tests where those functions been tested does not use
// roomDatabase.withTransaction { }
}
Gradle's files configuration
espresso_version = '3.2.0'
kotlin_coroutines_version = '1.3.3'
room_version = '2.2.5'
test_arch_core_testing = '2.1.0'
test_ext_junit_version = '1.1.1'
test_roboletric = '4.3.1'
test_runner_version = '1.2.0'
androidTestImplementation "androidx.arch.core:core-testing:$test_arch_core_testing"
androidTestImplementation "androidx.test.espresso:espresso-core:$espresso_version"
androidTestImplementation "androidx.test.ext:junit:$test_ext_junit_version"
androidTestImplementation "androidx.test:rules:$test_runner_version"
androidTestImplementation "androidx.test:runner:$test_runner_version"
androidTestImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:$kotlin_coroutines_version"

Last time I wrote a test for Room database I just simply use runBlock and it worked for me...
Could you take a look into this sample and check if it works for you as well?
Edit:
Ops! I missed this part... I tried this (in the same sample):
I defined a dummy function in my DAO using #Transaction
#Transaction
suspend fun quickInsert(book: Book) {
save(book)
delete(book)
}
I think this is the key of the problem. Add setTransactionExecutor to your Database instantiation.
appDatabase = Room.inMemoryDatabaseBuilder(
InstrumentationRegistry.getInstrumentation().context,
AppDatabase::class.java
).setTransactionExecutor(Executors.newSingleThreadExecutor())
.build()
Finally, the test worked using runBlocking
#Test
fun dummyTest() = runBlocking {
val dao = appDatabase.bookDao();
val id = dummyBook.id
dao.quickInsert(dummyBook)
val book = dao.bookById(id).first()
assertNull(book)
}
See this question.

I had tried many things to make this work, used runBlockingTest, used TestCoroutineScope, tried runBlocking, used allowMainThreadQueries, setTransactionExecutor, and setQueryExecutor on my in memory database.
But nothing worked until I found this comment thread in the Threading models in Coroutines and Android SQLite API article in the Android Developers Medium blog, other people mentioned running into this. Author Daniel Santiago said:
I’m not sure what Robolectric might be doing under the hood that could cause withTransaction to never return.
We usually don’t have Robolectric tests but we have plenty of Android Test examples if you want to try that route: https://android.googlesource.com/platform/frameworks/support/+/androidx-master-dev/room/integration-tests/kotlintestapp/src/androidTest/java/androidx/room/integration/kotlintestapp/test/SuspendingQueryTest.kt
I was able to fix my test by changing it from a Robolectric test to an AndroidTest and by using runBlocking
This is an example from the google source:
#Before
#Throws(Exception::class)
fun setUp() {
database = Room.inMemoryDatabaseBuilder(
ApplicationProvider.getApplicationContext(),
TestDatabase::class.java
)
.build()
booksDao = database.booksDao()
}
#Test
fun runSuspendingTransaction() {
runBlocking {
database.withTransaction {
booksDao.insertPublisherSuspend(
TestUtil.PUBLISHER.publisherId,
TestUtil.PUBLISHER.name
)
booksDao.insertBookSuspend(TestUtil.BOOK_1.copy(salesCnt = 0))
booksDao.insertBookSuspend(TestUtil.BOOK_2)
booksDao.deleteUnsoldBooks()
}
assertThat(booksDao.getBooksSuspend())
.isEqualTo(listOf(TestUtil.BOOK_2))
}
}

JUnit 5 - Parameterized Nested Tests

Expected
Creating a nested test within a parameterized test in JUnit5.
There are many conditions for the Android ViewModel using param. tests. I want to organize the tests within the param. test to improve output readability.
#ExtendWith(InstantExecutorExtension::class)
class ContentViewModelTest {
private fun `FeedLoad`() = Stream.of(
FeedLoadTest(isRealtime = false, feedType = MAIN, timeframe = DAY, lceState = LOADING),
FeedLoadTest(isRealtime = false, feedType = MAIN, timeframe = DAY, lceState = CONTENT))
#ParameterizedTest
#MethodSource("FeedLoad")
fun `Feed Load`(test: FeedLoadTest) {
#Nested
class FeedLoadNestedTest {
#Test
fun `all fields are included`() {
assertThat(4).isEqualTo(2 + 2)
}
#Test
fun `limit parameter`() {
assertThat(4).isEqualTo(3 + 2)
}
}
...
}
data class FeedLoadTest(val isRealtime: Boolean, val feedType: FeedType,
val timeframe: Timeframe, val lceState: LCE_STATE)
}
Observed
The normal parameterized assertions [not depicted] work as expected. The nested FeedLoadNestedTest does not run within the Stream of parameterized FeedLoad tests.

#Sam Brannen, thanks for the feedback!
Sam has indicated on GitHub, #Nested annotation on local classes will not be a viable option.
We have no plans to support #Nested on local classes defined within the scope of a method (function in Kotlin).
Solution
Implement multiple parameterized tests that pass in the same stream.
This will allow for assertions and logic to be organized into separate parameterized functions while testing the same data passed in via the stream.
#ParameterizedTest
#MethodSource("FeedLoadStream")
fun `Feed Load Part One`(test: FeedLoadTest) {
...
}
#ParameterizedTest
#MethodSource("FeedLoadStream")
fun `Feed Load Part Two`(test: FeedLoadTest) {
...
}
#ParameterizedTest
#MethodSource("FeedLoadStream")
fun `Feed Load Part Three`(test: FeedLoadTest) {
...
}

Mock suspend function return null because of different scopes

I am trying to test a ViewModel
class ViewModel {
val data = MutableLiveData<List<String>>()
val api = Api()
fun loadData(params: Map<String>) {
viewModelScope.launch {
data = api.fetchData(params) // return null LiveData here
}
}
}
class Api {
suspend fun fetchData(params: Map<String>): LiveData<List<String>>
}
And my test code is:
fun testFetchData() = runBlockingTest {
`when`(apiMock.fetchData(mapOf())).thenReturn(MutableLiveData(listOf("a", "b")))
viewModel.loadData(mapOf())
assertThat(viewModel.data.value).isEqualTo(listOf("a", "b"))
}
I run the test and it crashes because the Api.fetchData() does not return the mocked result - MutableLiveData(listOf("a", "b")) but it returns null. As far as I know, the reason is: the scope of runBlockingTest where I mock the function, and the scope of viewModelScope.launch where the function run is different.
Any suggestion to deal with this situation? better without changing ViewModel code

first of all, i believe you should pass Dispatcher to viewModel so in your test you can use Dispatcher.undefined..
and use this lib mockito-kotlin
second, in mockito you can use this code when you want to mock suspend
functions :
mockedObject.stub {
onBlocking { suspendFunction() }.doReturn(true)
}

Turn out the reason is because I mocked the wrong way
`when`(apiMock.fetchData(mapOf())).thenReturn(MutableLiveData(listOf("a", "b")))`
should use anyMap() instead of mapOf():
`when`(apiMock.fetchData(anyMap())).thenReturn(MutableLiveData(listOf("a", "b")))

Unit testing coroutines on UI thread

I'm using coroutines to do an asynchronous call on pull to refresh like so:
class DataFragment : Fragment(), SwipeRefreshLayout.OnRefreshListener {
// other functions here
override fun onRefresh() {
loadDataAsync()
}
private fun loadDataAsync() = async(UI) {
swipeRefreshLayout?.isRefreshing = true
progressLayout?.showContent()
val data = async(CommonPool) {
service?.getData() // suspending function
}.await()
when {
data == null -> showError()
data.isEmpty() -> progressLayout?.showEmpty(null, parentActivity?.getString(R.string.no_data), null)
else -> {
dataAdapter?.updateData(data)
dataAdapter?.notifyDataSetChanged()
progressLayout?.showContent()
}
}
swipeRefreshLayout?.isRefreshing = false
}
}
Everything here works fine when I actually put it on a device. My error, empty, and data states are all handled well and the performance is good. However, I'm also trying to unit test it with Spek. My Spek test looks like this:
#RunWith(JUnitPlatform::class)
class DataFragmentTest : Spek({
describe("The DataFragment") {
var uut: DataFragment? = null
beforeEachTest {
uut = DataFragment()
}
// test other functions
describe("when onRefresh") {
beforeEachTest {
uut?.swipeRefreshLayout = mock()
uut?.onRefresh()
}
it("sets swipeRefreshLayout.isRefreshing to true") {
verify(uut?.swipeRefreshLayout)?.isRefreshing = true // says no interaction with mock
}
}
}
}
The test is failing because it says that there was no interaction with the uut?.swipeRefreshLayout mock. After some experimenting, it seems this is because I'm using the UI context via async(UI). If I make it just be a regular async, I can get the test to pass but then the app crashes because I'm modifying views outside of the UI thread.
Any ideas why this might be occurring? Also, if anyone has any better suggestions for doing this which will make it more testable, I'm all ears.
Thanks.
EDIT: Forgot to mention that I also tried wrapping the verify and the uut?.onRefresh() in a runBlocking, but I still had no success.

If you want to make things clean and consider using MVP architecture in the future you should understand that CourutineContext is external dependency, that should be injected via DI, or passed to your presenter. More details on topic.
The answer for your question is simple, you should use only Unconfined CourutineContext for your tests. (more)
To make things simple create an object e.g. Injection with:
package com.example
object Injection {
val uiContext : CourutineContext = UI
val bgContext : CourutineContext = CommonPool
}
and in test package create absolutely the same object but change to:
package com.example
object Injection {
val uiContext : CourutineContext = Unconfined
val bgContext : CourutineContext = Unconfined
}
and inside your class it will be something like:
val data = async(Injection.bgContext) {service?.getData()}.await()