### Question:
Preconditions { public static <T> T checkNotNull(T argument) { return checkNotNull(argument, "Argument should be not null"); }  static T checkArgument(T argument, Function<T, Boolean> predicate, Object errorMessage); static T checkNotNull(T argument); static String checkNotNullOrEmpty(String argument, Object errorMessage); static T checkNotNull(T argument, Object errorMessage);  }### Answer:
@Test(expected = IllegalArgumentException.class) public void should_return_error_when_value_is_null(){ Preconditions.checkNotNull(null); }