assertTrue(isComparable.apply(2.0f));
    assertTrue(isComparable.apply(""));
    assertFalse(isComparable.apply(null));
  }

  @GwtIncompatible // Predicates.instanceOf
  public void testIsInstanceOf_equality() {
    new EqualsTester()
        .addEqualityGroup(
            Predicates.instanceOf(Integer.class), Predicates.instanceOf(Integer.class))
        .addEqualityGroup(Predicates.instanceOf(Number.class))