예제

@Getter
@NoArgsConstructor
class Model {

    private int id;
	  private String name;
	  
}

public class AssertJTest {
    @Test
    public void StringTest() {
        Model model = new Model(10, "Jackson");
        assertThat(model.getName()).isEqualTo("Jackson");
    
        assertThat(model.getName()).startsWith("Ja")
                        .endsWith("on")
                        .isEqualToIgnoringCase("jackson");
    }
    
    @Test
    public void ListTest() {
				Model samuel = new Model(1, "Samuel");
        Model jackson = new Model(2, "Jackson");
        Model matt = new Model(3, "Matt");
        Model nobody = new Model(4, "nobody");
				 List<Model> models = Stream.of(samuel, jackson, matt)
			                 .collect(toList());
				                 
				assertThat(models).hasSize(3)
			                .contains(samuel, matt, jackson)
			                .doesNotContain(nobody);
		}
				                    
	  @Test
    public void MapTest() {
		    Model samuel = new Model(1, "Samuel");
        Model jackson = new Model(2, "Jackson");
        Model matt = new Model(3, "Matt");
	      Model nobody = new Model(4, "nobody");
	      
        // when
        List<Model> models = Stream.of(samuel, jackson, matt)
                    .collect(toList());
                    
        Map<Integer, String> modelMap = models.stream()
                   .peek(System.out::println) // debug
                   .collect(Collectors.toMap(Model::getId, Model::getName));
                   
       assertThat(modelMap).hasSize(3)
                   .contains(entry(1, "Samuel"), entry(2, "Jackson"), entry(3, "Matt"))
                   .doesNotContainEntry(4, "nobody");
    }
}

Reference