assertThat(iia.indexOf(Double.MAX_VALUE)).isEqualTo(2);
    assertThat(iia.indexOf(Double.POSITIVE_INFINITY)).isEqualTo(3);
    assertThat(iia.indexOf(Double.NaN)).isEqualTo(4);
  }

  public void testLastIndexOf() {
    ImmutableDoubleArray iia = ImmutableDoubleArray.of(1, 1, 2, 3, 5, 8);
    assertThat(iia.lastIndexOf(1)).isEqualTo(1);
    assertThat(iia.lastIndexOf(8)).isEqualTo(5);

    assertThat(ImmutableIntArray.of(13).indexOf(13)).isEqualTo(0);
    assertThat(ImmutableIntArray.of().indexOf(21)).isEqualTo(-1);
    assertThat(iia.subArray(1, 5).indexOf(1)).isEqualTo(0);
  }

  public void testLastIndexOf() {
    ImmutableIntArray iia = ImmutableIntArray.of(1, 1, 2, 3, 5, 8);
    assertThat(iia.lastIndexOf(1)).isEqualTo(1);
    assertThat(iia.lastIndexOf(8)).isEqualTo(5);
    assertThat(iia.lastIndexOf(4)).isEqualTo(-1);

    assertThat(iia.indexOf(Double.MAX_VALUE)).isEqualTo(2);
    assertThat(iia.indexOf(Double.POSITIVE_INFINITY)).isEqualTo(3);
    assertThat(iia.indexOf(Double.NaN)).isEqualTo(4);
  }

  public void testLastIndexOf() {
    ImmutableDoubleArray iia = ImmutableDoubleArray.of(1, 1, 2, 3, 5, 8);
    assertThat(iia.lastIndexOf(1)).isEqualTo(1);
    assertThat(iia.lastIndexOf(8)).isEqualTo(5);