TestMonotonicFrameClock

A MonotonicFrameClock with a time source controlled by a kotlinx-coroutines-test TestCoroutineScheduler. This frame clock may be used to consistently drive time under controlled tests.

Calls to withFrameNanos will schedule an upcoming frame frameDelayNanos nanoseconds in the future by launching into coroutineScope if such a frame has not yet been scheduled. The current frame time for withFrameNanos is provided by delayController. It is strongly suggested that coroutineScope contain the test dispatcher controlled by delayController.

Summary

Public constructors
TestMonotonicFrameClock(
    coroutineScope: CoroutineScope,
    frameDelayNanos: Long,
    onPerformTraversals: (Long) -> Unit
)
android

Public functions
open suspend R
<R : Any?> withFrameNanos(onFrame: (frameTimeNanos: Long) -> R)

Schedules onFrame to be ran on the next "fake" frame, and schedules the task to actually perform that frame if it hasn't already been scheduled.
android

Public properties
ContinuationInterceptor

A CoroutineDispatcher that will defer continuation resumptions requested within withFrameNanos calls to until after the frame callbacks have finished running.
android
Long

The number of nanoseconds to delay between executing frames.
android
Boolean

Returns whether there are any awaiters on this clock.
android

Extension properties
Long

The frame delay time for the TestMonotonicFrameClock in milliseconds.
android

Inherited functions
From kotlin.coroutines.CoroutineContext
open operator CoroutineContext
android
From kotlin.coroutines.CoroutineContext.Element
open R
<R : Any?> fold(initial: R, operation: (CoroutineContext.Element, R) -> R)
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open operator E?
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open CoroutineContext
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Inherited properties
From androidx.compose.runtime.MonotonicFrameClock
open CoroutineContext.Key<*>
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Public constructors

TestMonotonicFrameClock

android
Added in 1.4.0
TestMonotonicFrameClock(
    coroutineScope: CoroutineScope,
    frameDelayNanos: Long = DefaultFrameDelay,
    onPerformTraversals: (Long) -> Unit = {}
)
Parameters
coroutineScope: CoroutineScope

The CoroutineScope used to simulate the main thread and schedule frames on. It must contain a TestCoroutineScheduler and a ContinuationInterceptor.
frameDelayNanos: Long = DefaultFrameDelay

The number of nanoseconds to delay between executing frames.
onPerformTraversals: (Long) -> Unit = {}

Called with the frame time of the frame that was just executed, after running all withFrameNanos callbacks, but before resuming their callers' continuations. Any continuations resumed while running frame callbacks or onPerformTraversals will not be dispatched until after onPerformTraversals finishes. If onPerformTraversals throws, all withFrameNanos callers will be cancelled.

Public functions

withFrameNanos

android 
open suspend fun <R : Any?> withFrameNanos(onFrame: (frameTimeNanos: Long) -> R): R

Schedules onFrame to be ran on the next "fake" frame, and schedules the task to actually perform that frame if it hasn't already been scheduled.

Instead of waiting for a vsync message to perform the next frame, it simply calls the coroutine delay function for the test frame time frameDelayMillis (which the underlying test coroutine scheduler will actually complete immediately without waiting), and then run all scheduled tasks.

Public properties

continuationInterceptor

android
Added in 1.4.0
@ExperimentalTestApi
val continuationInterceptor: ContinuationInterceptor

A CoroutineDispatcher that will defer continuation resumptions requested within withFrameNanos calls to until after the frame callbacks have finished running. Resumptions will then be dispatched before resuming the continuations from the withFrameNanos calls themselves.

frameDelayNanos

android
Added in 1.0.0
val frameDelayNanos: Long

The number of nanoseconds to delay between executing frames.

hasAwaiters

android
Added in 1.0.0
val hasAwaiters: Boolean

Returns whether there are any awaiters on this clock.

Extension properties

frameDelayMillis

android 
@ExperimentalTestApi
val TestMonotonicFrameClock.frameDelayMillis: Long

The frame delay time for the TestMonotonicFrameClock in milliseconds.