a284628487
commented
3 years ago ViewMode & LiveData
MainViewModel
import android.app.Application
import androidx.lifecycle.AndroidViewModel
import androidx.lifecycle.MutableLiveData
class MainViewModel(app: Application) : AndroidViewModel(app) {
fun doubled(input: Int): Int {
return input * 2
}
fun formatTime(hour: Int, minute: Int): String {
return getApplication<Application>().getString(R.string.time_format, hour, minute)
}
private val _resultLiveData = MutableLiveData<Int>()
val resultLiveData = _resultLiveData
fun commitPreResult(input: Int) {
if (input > 5) {
_resultLiveData.postValue(100)
} else {
_resultLiveData.postValue(input * 20)
}
}
}MainViewModelTest
import android.app.Application
import androidx.arch.core.executor.testing.InstantTaskExecutorRule
import androidx.test.core.app.ApplicationProvider
import androidx.test.ext.junit.runners.AndroidJUnit4
import org.junit.After
import org.junit.Before
import org.junit.Test
import org.junit.Assert.*
import org.junit.Rule
import org.junit.runner.RunWith
@RunWith(AndroidJUnit4::class)
class MainViewModelTest {
@get:Rule
var instantExecutorRule = InstantTaskExecutorRule()
lateinit var viewModel: MainViewModel
@Before
fun setUp() {
val applicationContext = ApplicationProvider.getApplicationContext<Application>()
viewModel = MainViewModel(applicationContext)
}
@After
fun tearDown() {
}
@Test
fun doubled_input10_return20() {
val result = viewModel.doubled(10)
println("doubled_input10_return20: ${result}")
assertEquals(result, 20)
}
@Test
fun formatTime_inputHour10Min10_return10H10m() {
val result = viewModel.formatTime(10, 10)
println("formatTime_inputHour10Min10_return10H10m: ${result}")
assertEquals(result, "10H:10m")
}
@Test
fun commitPreResult_input2_return40() {
viewModel.commitPreResult(2)
val result = viewModel.resultLiveData.getOrAwaitValue()
println("commitPreResult_input2_return40: ${result}")
assertEquals(result, 40)
}
}LiveDataTestUtil
import androidx.annotation.VisibleForTesting
import androidx.lifecycle.LiveData
import androidx.lifecycle.Observer
import java.util.concurrent.CountDownLatch
import java.util.concurrent.TimeUnit
import java.util.concurrent.TimeoutException
@VisibleForTesting(otherwise = VisibleForTesting.NONE)
fun <T> LiveData<T>.getOrAwaitValue(
time: Long = 5,
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()
this@getOrAwaitValue.removeObserver(this)
}
}
this.observeForever(observer)
try {
afterObserve.invoke()
// Don't wait indefinitely if the LiveData is not set.
if (!latch.await(time, timeUnit)) {
throw TimeoutException("LiveData value was never set.")
}
} finally {
this.removeObserver(observer)
}
@Suppress("UNCHECKED_CAST")
return data as T
}
dependencies