@Test
 public void should_return_this() {
   ConcreteAssert descriptable = assertions.as(d);
   assertSame(assertions, descriptable);
 }
 @Test
 public void should_throw_error_if_description_is_null() {
   thrown.expectNullPointerException(descriptionIsNull());
   assertions.as((Description) null);
 }
 @Test
 public void should_set_description() {
   assertions.as(d);
   assertEquals(d.value(), assertions.descriptionText());
 }