Mocking the return value of System.currentTimeMillis() with JMockit

• July 20, 2016
• java, testing

Having the ability to mock the return value of System.currentTimeMillis() can be very useful when testing time-sensitive code. The following is an example of how to accomplish the mocking of System.currentTimeMillis() to return any desired value, easily with JMockit 1.25.

 import java.util.Date;  
 import mockit.Mock;  
 import mockit.MockUp;  
   
 public class Tester {  
   
  private static class SystemMock extends MockUp<System> {  
    @Mock  
    public static long currentTimeMillis() {  
     return 10000000L;  
    }  
  }  
   
  public void doSomethingWithDates() {  
    new SystemMock();  
    System.out.println(new Date());  
  }  
   
  public static void main(String args[]) {  
    Tester t = new Tester();  
    t.doSomethingWithDates();  
  }  
   
 }  

Thanks to trunkc for providing the answer on this StackOverflow thread: http://stackoverflow.com/questions/31750244/jmockit-mocking-system-currenttimemillis