code: public void testQueryByProcessInstanceIds(){
    Set<String> processInstanceIds=new HashSet<String>(this.processInstanceIds);
    runtimeService.startProcessInstanceByKey("oneTaskProcess2","2");
    ProcessInstanceQuery processInstanceQuery=runtimeService.createProcessInstanceQuery().processInstanceIds(processInstanceIds);
    assertEquals(5,processInstanceQuery.count());
    List<ProcessInstance> processInstances=processInstanceQuery.list();
    assertNotNull(processInstances);
    assertEquals(5,processInstances.size());
    for (  ProcessInstance processInstance : processInstances) {
      assertTrue(processInstanceIds.contains(processInstance.getId()));
    }
  }
  