@Test
  public void testSetStartingOffset() {
    SystemStreamPartition ssp = new SystemStreamPartition("mySystem", "myStream", new Partition(0));
    taskContext.setStartingOffset(ssp, "123");
    verify(offsetManager).setStartingOffset(TASK_NAME, ssp, "123");
  }
Given an SSP and offset, setStartingOffset should delegate to the offset manager.
samza-core/src/test/java/org/apache/samza/context/TestTaskContextImpl.java