java - Running multiple threads from within a unit test -

below unit test uses scheduledexecutorservice execute scheduled runnable every second :

   import java.util.concurrent.executorservice; import java.util.concurrent.executors; import java.util.concurrent.scheduledexecutorservice; import java.util.concurrent.timeunit;  import org.junit.test;  public class concurrentrequestsimulator {      private static final int number_requests = 4;      @test     public void testgettodolist() {          try {             scheduledexecutorservice scheduler = executors.newscheduledthreadpool(10);             scheduler.scheduleatfixedrate(new requestthreadinvoker(), 0, 1, timeunit.seconds);         } catch (exception e) {             e.printstacktrace();         }     }      private final class requestthreadinvoker implements runnable {          public void run() {              executorservice es = executors.newcachedthreadpool();             (int = 1; <= number_requests; i++) {                 es.execute(new requestthread());             }             es.shutdown();              while (!es.isterminated()) {              }          }     }      private final class requestthread implements runnable {          public void run() {             try {                 system.out.println("in requestthread");                 thread.sleep(1000);             } catch (interruptedexception e) {                 e.printstacktrace();             }         }     }  } 

the line system.out.println("in requestthread"); in requestthread not appear invoked no output displayed console. think issue since test runs completion, causes scheduler stop scheduling? can test updated scheduler not terminated , requestthreadinvoker invoked repeatedly once per second ?

in requestthreadinvoker create new instance of executorservice. causing issue ?

adding thread.sleep(99000); end of test causes test wait 99 seconds enough time test run.