### Question:
Assert { public static void notNull(Object obj, String message) { if (obj == null) { throw new IllegalArgumentException(message); } } private  Assert(); static void notNull(Object obj, String message); static void notEmpty(String string, String message); static void notEmpty(Collection<?> collection, String message); static void maxLength(String string, int max);  }### Answer:
@Test public void not_null_with_null_throws_illegal_argument() { expected.expect(IllegalArgumentException.class); Assert.notNull(null, "message"); }
@Test public void not_null_with_null_even_when_message_is_null_throws_illegal_argument() { expected.expect(IllegalArgumentException.class); Assert.notNull(null, null); }
@Test public void not_null_with_not_null_throws_no_exception() { Assert.notNull("not null...", "message"); }
@Test public void not_null_with_not_null_null_message_throws_no_exception() { Assert.notNull("not null...", null); }