@Test
public void testInvalidNames() {

  assertAll(
      () -> assertThrows(NullPointerException.class, () -> Category.of(null)),
      () -> assertThrows(IllegalArgumentException.class, () -> Category.of("")),
      () -> assertThrows(IllegalArgumentException.class, () -> Category.of(" ")),
      () -> assertThrows(IllegalArgumentException.class, () -> Category.of("\n")),
      () -> assertThrows(IllegalArgumentException.class, () -> Category.of("\t"))
  );
}