@UnstableApi
public class FakeClock implements Clock

Fake Clock implementation that allows to advance the time manually to trigger pending timed messages.

All timed messages sent by a Handler created from this clock are governed by the clock's time. Messages sent through these handlers are not triggered until previous messages on any thread have been handled to ensure deterministic execution. Note that this includes messages sent from the main Robolectric test thread, meaning that these messages are only triggered if the main test thread is idle, which can be explicitly requested by calling ShadowLooper.idleMainLooper().

The clock also sets the time of the SystemClock to match the clock's time.

Summary

Nested types
protected final inner class FakeClock.HandlerMessage implements Comparable, HandlerWrapper.Message

Message data saved to send messages or execute runnables at a later time on a Handler.

Public constructors
FakeClock(long initialTimeMs)

Creates a fake clock that doesn't auto-advance and assumes that the system was booted exactly at time 0 (the Unix Epoch) and initialTimeMs milliseconds have passed since system boot.
FakeClock(boolean isAutoAdvancing)

Creates a fake clock that assumes that the system was booted exactly at time 0 (the Unix Epoch) and an initialTimeMs of 0.
FakeClock(long initialTimeMs, boolean isAutoAdvancing)

Creates a fake clock that assumes that the system was booted exactly at time 0 (the Unix Epoch) and initialTimeMs milliseconds have passed since system boot.
FakeClock(long bootTimeMs, long initialTimeMs, boolean isAutoAdvancing)

Creates a fake clock specifying when the system was booted and how much time has passed since then.

Public methods
synchronized void
advanceTime(long timeDiffMs)

Advance timestamp of FakeClock by the specified duration.
HandlerWrapper

Creates a HandlerWrapper using a specified looper and a specified callback for handling messages.
synchronized long

Returns the current time in milliseconds since the Unix Epoch.
synchronized long
synchronized long

See nanoTime
synchronized void

Notifies the clock that the current thread is about to be blocked and won't return until a condition on another thread becomes true.
long

Protected methods
synchronized void

Adds a message to the list of pending messages.

Inherited Constants
From androidx.media3.common.util.Clock
static final Clock

Default Clock to use for all non-test cases.

Public constructors

FakeClock

public FakeClock(long initialTimeMs)

Creates a fake clock that doesn't auto-advance and assumes that the system was booted exactly at time 0 (the Unix Epoch) and initialTimeMs milliseconds have passed since system boot.

Parameters
long initialTimeMs

The initial elapsed time since the boot time, in milliseconds.

FakeClock

public FakeClock(boolean isAutoAdvancing)

Creates a fake clock that assumes that the system was booted exactly at time 0 (the Unix Epoch) and an initialTimeMs of 0.

Parameters
boolean isAutoAdvancing

Whether the clock should automatically advance the time to the time of next message that is due to be sent.

FakeClock

public FakeClock(long initialTimeMs, boolean isAutoAdvancing)

Creates a fake clock that assumes that the system was booted exactly at time 0 (the Unix Epoch) and initialTimeMs milliseconds have passed since system boot.

Parameters
long initialTimeMs

The initial elapsed time since the boot time, in milliseconds.
boolean isAutoAdvancing

Whether the clock should automatically advance the time to the time of next message that is due to be sent.

FakeClock

public FakeClock(long bootTimeMs, long initialTimeMs, boolean isAutoAdvancing)

Creates a fake clock specifying when the system was booted and how much time has passed since then.

Parameters
long bootTimeMs

The time the system was booted since the Unix Epoch, in milliseconds.
long initialTimeMs

The initial elapsed time since the boot time, in milliseconds.
boolean isAutoAdvancing

Whether the clock should automatically advance the time to the time of next message that is due to be sent.

Public methods

advanceTime

synchronized public void advanceTime(long timeDiffMs)

Advance timestamp of FakeClock by the specified duration.

Parameters
long timeDiffMs

The amount of time to add to the timestamp in milliseconds.

createHandler

public HandlerWrapper createHandler(
    Looper looper,
    @UnknownInitialization @Nullable @UnknownInitialization Handler.Callback callback
)

Creates a HandlerWrapper using a specified looper and a specified callback for handling messages.

See also
Handler

currentTimeMillis

synchronized public long currentTimeMillis()

Returns the current time in milliseconds since the Unix Epoch.

See also
currentTimeMillis

elapsedRealtime

synchronized public long elapsedRealtime()
See also
elapsedRealtime

nanoTime

synchronized public long nanoTime()

See nanoTime

onThreadBlocked

synchronized public void onThreadBlocked()

Notifies the clock that the current thread is about to be blocked and won't return until a condition on another thread becomes true.

Should be a no-op for all non-test cases.

uptimeMillis

public long uptimeMillis()
See also
uptimeMillis

Protected methods

addPendingHandlerMessage

synchronized protected void addPendingHandlerMessage(FakeClock.HandlerMessage message)

Adds a message to the list of pending messages.