Time dependent unit tests

Question

I need to test a function that whose result will depend on current time (using Joda time\'s isBeforeNow(), it so happens).

public boolean isAvai         


        

Answer 1

To add to Jon Skeet's answer, Joda Time already contains a current time interface: DateTimeUtils.MillisProvider

For example:

import org.joda.time.DateTime;
import org.joda.time.DateTimeUtils.MillisProvider;

public class Check {
    private final MillisProvider millisProvider;
    private final DateTime someDate;

    public Check(MillisProvider millisProvider, DateTime someDate) {
        this.millisProvider = millisProvider;
        this.someDate = someDate;
    }

    public boolean isAvailable() {
        long now = millisProvider.getMillis();
        return (someDate.isBefore(now));
    }
}

Mock the time in a unit test (using Mockito but you could implement your own class MillisProviderMock):

DateTime fakeNow = new DateTime(2016, DateTimeConstants.MARCH, 28, 9, 10);
MillisProvider mockMillisProvider = mock(MillisProvider.class);
when(mockMillisProvider.getMillis()).thenReturn(fakeNow.getMillis());

Check check = new Check(mockMillisProvider, someDate);

Use the current time in production (DateTimeUtils.SYSTEM_MILLIS_PROVIDER was added to Joda Time in 2.9.3):

Check check = new Check(DateTimeUtils.SYSTEM_MILLIS_PROVIDER, someDate);