@Test(expected = IllegalArgumentException.class)
  public void testGetTaskNamesForProcessorWithNullProcessorId() {
    JobModelUtil.getTaskNamesForProcessor(null, mock(JobModel.class));
  }
Tests the following scenarios as part of the same tests to reduce boiler plate and potentially allow
parallel executions of tests for the class.
 1. Test null job models for processors
 2. Test same container models across job models for processors
 3. Test different container models across job models for processors
 4. Test absence of container model vs presence across job models for processors

The approach below leans towards performance (parallel execution) as opposed to readability; i.e sharing setup of
the tests and having multiple tests that test individual scenarios. Additionally, the individual scenarios being
tested are self explanatory.
samza-core/src/test/java/org/apache/samza/job/model/TestJobModelUtil.java