@Test(expected = SamzaException.class)
  public void testApplyRewriterClassDoesNotExist() {
    Map<String, String> fullConfig =
        ImmutableMap.of(CONFIG_KEY, CONFIG_VALUE, String.format(JobConfig.CONFIG_REWRITER_CLASS, REWRITER_NAME),
            "not_a_class");
    Config expectedConfig = new MapConfig(ImmutableMap.of(CONFIG_KEY, CONFIG_VALUE, NEW_CONFIG_KEY, CONFIG_VALUE));
    assertEquals(expectedConfig, ConfigUtil.applyRewriter(new MapConfig(fullConfig), REWRITER_NAME));
  }
This fails because Util will interpret the empty string value as a single rewriter which has the empty string as a
name, and there is no rewriter class config for a rewriter name which is the empty string.
TODO: should this be fixed to interpret the empty string as an empty list?
samza-core/src/test/java/org/apache/samza/util/TestConfigUtil.java