input = Arrays.copyOf(input, input.length);
    Longs.reverse(input, fromIndex, toIndex);
    assertThat(input).isEqualTo(expectedOutput);
  }

  public void testReverseIndexed() {
    testReverse(new long[] {}, 0, 0, new long[] {});
    testReverse(new long[] {1}, 0, 1, new long[] {1});
    testReverse(new long[] {1, 2}, 0, 2, new long[] {2, 1});