@Test
  public void testCommaSeparated() {
    String commaSeparated1 = Utils.commaSeparated("foo");
    assertEquals("foo", commaSeparated1);

    String commaSeparated2 = Utils.commaSeparated("foo", "bar", "");
    assertEquals("foo,bar", commaSeparated2);

    String commaSeparated3 = Utils.commaSeparated("foo", "bar", null);
    assertEquals("foo,bar", commaSeparated3);

    String commaSeparated4 = Utils.commaSeparated();
    assertEquals("", commaSeparated4);
  }
This class tests the Utils class
test/com/linkedin/drelephant/util/UtilsTest.java