SomeCheckedException exception = new SomeCheckedException();
    assertSame(exception, getRootCause(exception));
  }

  public void testGetRootCause_singleWrapped() {
    SomeCheckedException cause = new SomeCheckedException();
    SomeChainingException exception = new SomeChainingException(cause);
    assertSame(cause, getRootCause(exception));
  }

  public void testGetRootCause_doubleWrapped() {

    SomeCheckedException exception = new SomeCheckedException();
    assertSame(exception, getRootCause(exception));
  }

  public void testGetRootCause_singleWrapped() {
    SomeCheckedException cause = new SomeCheckedException();
    SomeChainingException exception = new SomeChainingException(cause);
    assertSame(cause, getRootCause(exception));
  }

  public void testGetRootCause_doubleWrapped() {

   *
   * <pre>
   * assertEquals("Unable to assign a customer id", Throwables.getRootCause(e).getMessage());
   * </pre>
   *
   * @throws IllegalArgumentException if there is a loop in the causal chain
   */
  public static Throwable getRootCause(Throwable throwable) {
    // Keep a second pointer that slowly walks the causal chain. If the fast pointer ever catches