@Test public void testFindClientsByPetName() throws Exception { List<Client> clients = new ArrayList<>(); Client client1 = new Client(1, "Vasya"); client1.addPet("Cat", "Pushok"); Client client2 = new Client(2, "Fedor"); client2.addPet("Cat", "Pushok"); client2.addPet("Dog", "Bull"); clients.add(client1); clients.add(client2); assertEquals(myClinic.findClientsByPetName("Pushok"), clients); }