60 lines
1.6 KiB
Kotlin
60 lines
1.6 KiB
Kotlin
package org.thoughtcrime.securesms
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import androidx.annotation.VisibleForTesting
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import androidx.lifecycle.LiveData
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import androidx.lifecycle.Observer
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import java.util.concurrent.CountDownLatch
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import java.util.concurrent.TimeUnit
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import java.util.concurrent.TimeoutException
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/**
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* Gets the value of a [LiveData] or waits for it to have one, with a timeout.
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*
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* Use this extension from host-side (JVM) tests. It's recommended to use it alongside
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* `InstantTaskExecutorRule` or a similar mechanism to execute tasks synchronously.
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*/
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@VisibleForTesting(otherwise = VisibleForTesting.NONE)
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fun <T> LiveData<T>.getOrAwaitValue(
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time: Long = 2,
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timeUnit: TimeUnit = TimeUnit.SECONDS,
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afterObserve: () -> Unit = {}
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): T {
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var data: T? = null
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val latch = CountDownLatch(1)
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val observer = object : Observer<T> {
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override fun onChanged(o: T?) {
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data = o
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latch.countDown()
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this@getOrAwaitValue.removeObserver(this)
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}
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}
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this.observeForever(observer)
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try {
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afterObserve.invoke()
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// Don't wait indefinitely if the LiveData is not set.
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if (!latch.await(time, timeUnit)) {
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throw TimeoutException("LiveData value was never set.")
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}
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} finally {
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this.removeObserver(observer)
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}
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@Suppress("UNCHECKED_CAST")
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return data as T
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}
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/**
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* Observes a [LiveData] until the `block` is done executing.
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*/
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fun <T> LiveData<T>.observeForTesting(block: () -> Unit) {
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val observer = Observer<T> { }
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try {
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observeForever(observer)
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block()
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} finally {
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removeObserver(observer)
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}
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} |