public void testNextDown() throws Exception {
    Method jdkNextDown = getJdkNextDown();
    for (double d : FINITE_DOUBLE_CANDIDATES) {
      assertEquals(jdkNextDown.invoke(null, d), DoubleUtils.nextDown(d));
    }
  }

  private static Method getJdkNextDown() throws Exception {
    try {
      return Math.class.getMethod("nextDown", double.class);