FluentIterable<TimeUnit> units = FluentIterable.from(TimeUnit.values());
    assertThrows(UnsupportedOperationException.class, () -> removeIf(units, equalTo(SECONDS)));
  }

  public void testFrom() {
    assertEquals(
        ImmutableList.of(1, 2, 3, 4),
        Lists.newArrayList(FluentIterable.from(ImmutableList.of(1, 2, 3, 4))));
  }

  @SuppressWarnings({
    "deprecation", // test of deprecated method

    assertThrows(NullPointerException.class, () -> comparator.compare(null, null));
    assertSame(comparator, reserialize(comparator));
    assertEquals("Ordering.natural()", comparator.toString());
  }

  public void testFrom() {
    Ordering<String> caseInsensitiveOrdering = Ordering.from(String.CASE_INSENSITIVE_ORDER);
    assertEquals(0, caseInsensitiveOrdering.compare("A", "a"));
    assertTrue(caseInsensitiveOrdering.compare("a", "B") < 0);

    assertThrows(NullPointerException.class, () -> comparator.compare(null, null));
    assertSame(comparator, reserialize(comparator));
    assertEquals("Ordering.natural()", comparator.toString());
  }

  public void testFrom() {
    Ordering<String> caseInsensitiveOrdering = Ordering.from(String.CASE_INSENSITIVE_ORDER);
    assertEquals(0, caseInsensitiveOrdering.compare("A", "a"));
    assertTrue(caseInsensitiveOrdering.compare("a", "B") < 0);