@PostContruct方法不适用于Mockito

Question

您好，我正在尝试使用PostConstruct方法初始化字段，但在测试中，此方法不会填充bidiMap字段。

有没有办法模拟bidiMap字段，它是DataSource的字段？

@Component
@Getter
@Setter
@NoArgsConstructor
public class DataSource {

    public DualHashBidiMap<String, String> bidiMap = new DualHashBidiMap();

    @PostConstruct
    public void loadData() throws IOException {
        Map<String, String> data = new ObjectMapper().readValue(new File("src/main/resources/static/data.json"), Map.class);
        data.entrySet().stream().forEach(item -> this.bidiMap.put(item.getKey(), item.getValue()));
    }
}

测试：

@Test
    void shouldReturnPrettifiedUrl_WithQueryParams() throws IOException {
        // Given
        List<String> inputParameters = Arrays.asList("/products?gender=female&tag=123&tag=1234");
        HashMap<String, String> expectedResult = PrettyUrlResponseBuilder.PrettyUrlResponseBuilder().createPrettyUrlResponseWithParams();
        HashMap<String, String> databaseResponse = DatabaseResponse.DatabaseResponse().createDatabaseResponse();
        System.out.println(dataSource);
        // When
        Map<String, String> actualResult = prettyUrlService.toPretty(inputParameters);

        // Then
        assertEquals(expectedResult, actualResult);
    }

正在测试的类：

@Service
public class PrettyUrlService {
    private final DataSource dataSource;

    public PrettyUrlService(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    public Map<String, String> toPretty(List<String> urlList) throws IOException {
        var data = dataSource.getBidiMap(); // Here, data is null.
        // ...
    }
}

Answer 1

如果您正在单元测试PrettyUrlService类，那么您不需要在同一测试中也测试底层的数据源类。只需模拟数据源的交互并验证所有预期的交互都在发生就足够了。

例如（假设JUnit 5）：

@ExtendWith(MockitoExtension.class)
class PrettyUrlServiceTest {

  @Mock
  private DataSource dataSource;
  private PrettyUrlService prettyUrlService;

  @BeforeEach
  void setUp() {
    prettyUrlService = new PrettyUrlService(dataSource);
  }

  @Test
  void exampleTest() {
    DualHashBidiMap<String, String> bidiMap = new DualHashBidiMap();
    // add test data to the map
    bidiMap.put("testKey", "testValue"); // replace with data you need for test
    Mockito.when(dataSource.getBidiMap()).thenReturn(bidiMap);
    
    // insert test logic here (prettyServiceUrl call + assertions)
    // ...

    // finally, verify that dataSource.getBidiMap() was called exactly once
    Mockito.verify(dataSource).getBidiMap();
  }

}