Jordi P.S. Jordi P.S. - 8 months ago 653
Java Question

How to mock new Date() in java using Mockito

I have a function that uses the current time to make some calculations. I'd like to mock it using mockito.

An example of the class I'd like to test:

public class ClassToTest {
public long getDoubleTime(){
return new Date().getTime()*2;

I'd like something like:

public void testDoubleTime(){
assertEquals(60,new ClassToTest().getDoubleTime());

Is it possible to mock that? I wouldn't like to change the "tested" code in order to be tested.


The right thing to do is to restructure your code to make it more testable as shown below. Restructuring your code to remove the direct dependency on Date will allow you to inject different implementations for normal runtime and test runtime:

interface DateTime {
    Date getDate();

class DateTimeImpl implements DateTime {
    public Date getDate() {
       return new Date();

class MyClass {

    private final DateTime dateTime;
    // inject your Mock DateTime when testing other wise inject DateTimeImpl

    public MyClass(final DateTime dateTime) {
        this.dateTime = dateTime;

    public long getDoubleTime(){
        return dateTime.getDate().getTime()*2;

public class MyClassTest {
    private MyClass myClassTest;

    public void setUp() {
        final Date date = Mockito.mock(Date.class);

        final DateTime dt = Mockito.mock(DateTime.class);

        myClassTest = new MyClass(dt);

    public void someTest() {
        final long doubleTime = myClassTest.getDoubleTime();
        assertEquals(60, doubleTime);