assertThat(before.get(3).toString(), equalTo("Duo{id=4, a=B, b=A}"));
assertThat(before.get(4).toString(), equalTo("Duo{id=5, a=B, b=B}"));
assertThat(before.get(5).toString(), equalTo("Duo{id=6, a=B, b=C}"));
Duo duo = new Duo("XXX", "ZZZ");
atomicMerge.update(duo).with(new PrimaryKey(3));
List<Duo> after = findAll();
assertThat(after.size(), equalTo(6));
assertThat(after.get(0).toString(), equalTo("Duo{id=1, a=A, b=A}"));