@Test
public void even_a_null_message_results_in_error() {

	/* prepare */
	String message = null;
	/* execute */
	AsciiDoctorMarker error = builderToTest.build(message);
	/* test */
	assertNotNull(error);
	assertEquals(-1, error.getStart());
	assertEquals(-1, error.getEnd());
	assertEquals(Type.ERROR, error.getType());
	assertEquals("Unknown failure", error.getMessage());
}