Package pl.amazingcode.timeflow

Class TestTime

java.lang.Object

pl.amazingcode.timeflow.Time

pl.amazingcode.timeflow.TestTime

public final class TestTime
extends Time

TestTime is a singleton class that provides access to the current time and allows to manipulate it both in production and test code. It is an extension of Time. TestTime is designed to be used in tests only.

Method Summary

Modifier and Type	Method	Description
void	clearObservers()	Remove all registered observers.
Clock	clock()	Returns the clock.
void	fastBackward(Duration duration)	Jump the clock backward by the given duration.
void	fastForward(Duration duration)	Jump the clock forward by the given duration.
Instant	now()	Returns the current instant using the clock.
void	registerObserver(Consumer<Clock> clockConsumer)	Register an observer that will be notified every time the clock is changed by fastForward(Duration), fastBackward(Duration) or timeFlow(Duration, Instant, int).
void	resetClock()	Reset the clock used by Time and TestTime with current time using Clock.systemUTC().
void	setClock(Clock clock)	Replace the clock used by Time and TestTime with a custom one.
static TestTime	testInstance()	Returns the singleton instance of TestTime.
void	timeFlow(Duration step, Instant endTime, int flowSpeedMillis)	Simulate time flow by jumping the clock forward by the given step every flowSpeedMillis.

Methods inherited from class pl.amazingcode.timeflow.Time

instance

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

testInstance

public static TestTime testInstance()

Returns the singleton instance of TestTime.

Returns:

the singleton instance of TestTime

now

public Instant now()

Returns the current instant using the clock.

Overrides:

now in class Time

Returns:

the current instant

clock

public Clock clock()

Returns the clock. Inner clock is instantiated with Clock.systemUTC().

Overrides:

clock in class Time

Returns:

the clock

setClock

public void setClock(Clock clock)

Replace the clock used by Time and TestTime with a custom one.

    // Prepare a fixed clock
    ZoneId zoneId = TimeZone.getTimeZone("Europe/Warsaw").toZoneId();
    ZonedDateTime dateTime = LocalDateTime.of(2001, 11, 23, 12, 15).atZone(zoneId);
    Clock fixedClock = Clock.fixed(dateTime.toInstant(), zoneId);

    // Set the fixed clock as the clock used by Time in the production code
    TestTime.testInstance().setClock(fixedClock);
 

Overrides:

setClock in class Time

Parameters:

clock -

resetClock

public void resetClock()

Reset the clock used by Time and TestTime with current time using Clock.systemUTC().

fastForward

public void fastForward(Duration duration)

Jump the clock forward by the given duration.

Parameters:

duration - the duration to jump forward

fastBackward

public void fastBackward(Duration duration)

Jump the clock backward by the given duration.

Parameters:

duration - the duration to jump backward

timeFlow

public void timeFlow(Duration step,
                     Instant endTime,
                     int flowSpeedMillis)

Simulate time flow by jumping the clock forward by the given step every flowSpeedMillis. This will replace the clock used by Time in the production code.

    // Prepare a fixed clock
    ZoneId zoneId = TimeZone.getTimeZone("Europe/Warsaw").toZoneId();
    ZonedDateTime dateTime = LocalDateTime.of(2001, 11, 23, 12, 15).atZone(zoneId);
    Clock fixedClock = Clock.fixed(dateTime.toInstant(), zoneId);

    // Set the fixed clock as the clock used by Time in the production code
    TestTime.testInstance().setClock(fixedClock);

    // Prepare time flow parameters
    Duration step = Duration.of(1, ChronoUnit.MINUTES);
    Instant endTime = fixedClock.instant().plus(10, ChronoUnit.MINUTES);
    int flowSpeedMillis = 100;

    // Simulate time flow
    TestTime.testInstance().timeFlow(step, endTime, flowSpeedMillis);
 

Parameters:

step - the duration to jump forward

endTime - the time when the simulated time flow should stop

flowSpeedMillis - the speed of the simulated time flow in milliseconds

Throws:

IllegalArgumentException - if flowSpeedMillis is not positive or endTime is before the current time

RuntimeException - if interrupted while sleeping between jumps

registerObserver

public void registerObserver(Consumer<Clock> clockConsumer)

Register an observer that will be notified every time the clock is changed by fastForward(Duration), fastBackward(Duration) or timeFlow(Duration, Instant, int).

    TestTime
        .testInstance()
        .registerObserver(clock -> System.out.println(clock.instant()));
 

Parameters:

clockConsumer - the observer

clearObservers

public void clearObservers()

Remove all registered observers.