@Test
public void returnsUnmodifiedModelIfToAndFromAreEqual() {

    ShapeId stringId = ShapeId.from("ns.foo#String");
    StringShape target = StringShape.builder().id(stringId).build();
    Model model = Model.builder()
            .addShapes(target)
            .build();
    ModelTransformer transformer = ModelTransformer.create();
    Map<ShapeId, ShapeId> renamed = new HashMap<>();
    renamed.put(stringId, stringId );
    Model result = transformer.renameShapes(model, renamed);
    assertEquals(result.shapes().count(), 1);
    assertEquals(result.getShape(stringId).get(), target);
}