@Test
  public void testBasicSingleStream() {
    addStreamMetadataCacheMetadata(this.streamMetadataCache,
        ImmutableMap.of(SYSTEM_STREAM0, buildSystemStreamMetadata(4)));
    Map<TaskName, Integer> changeLogPartitionMapping = changelogPartitionMapping(4);
    Config config = config(ImmutableList.of(SYSTEM_STREAM0), ImmutableMap.of());
    Map<String, ContainerModel> containerModels = ImmutableMap.of("0",
        new ContainerModel("0", ImmutableMap.of(taskName(0), taskModel(0, 0), taskName(2), taskModel(2, 2))), "1",
        new ContainerModel("1", ImmutableMap.of(taskName(1), taskModel(1, 1), taskName(3), taskModel(3, 3))));
    JobModel expected = new JobModel(config, containerModels);
    JobModel actual =
        JobModelCalculator.INSTANCE.calculateJobModel(config, changeLogPartitionMapping, this.streamMetadataCache,
            this.grouperMetadata);
    assertEquals(expected, actual);
  }
Unfortunately, we still need powermock for testing the regex topic flow, since that flow checks for a specific
rewriter class, and setting up the support for that specific class is too cumbersome.
Many of the tests do not need powermock.
samza-core/src/test/java/org/apache/samza/coordinator/TestJobModelCalculator.java