Java 17 SpringBoot应用JUnit测试时RetrySynchronizationManager.getContext()为空

基于Java 17开发的SpringBoot应用中，重试逻辑功能运行正常，但编写JUnit测试用例时触发空指针异常，报错RetrySynchronizationManager.getContext()返回null。

方法代码 #

@Retryable(maxAttemptsExpression = "${retry.maxRetry}", 
backoff = @Backoff(delayExpression = "${retry.maxInterval}",
            multiplierExpression = "${retry.delayMultiplier}", maxDelayExpression = "${retry.maxDelay}"))
public Session connect() {
    retryCountConnect = RetrySynchronizationManager.getContext().getRetryCount();
    Session sshSession = null;
    try {
        sshSession = sshSessionPool.getSession();
        sshSession.connect();
        return sshSession;
    } catch (Exception e) {
        log.error("Exception occurred during SshSftp connect, retry count:{}, error details:{}",
                retryCountConnect, ExceptionUtils.getStackTrace(e));
        throw new RuntimeException(e);
    }
}

测试用例代码 #

class ConnectionTest {
    @Mock
    Session sshSession;
    @Mock
    SshSessionPool sshSessionPool;
    @Mock
    MockedStatic<BasicSshSessionPool> basicSshSessionPoolMockedStatic;
    @Mock
    MockedStatic<AopContext> aopContext;
    Channel channel;
    SshSftpConnection sshSftpConnection;

    @BeforeEach
    @SneakyThrows
    void setUp() {
        channel = Mockito.mock(ChannelExec.class);
        MockitoAnnotations.openMocks(this);
        basicSshSessionPoolMockedStatic.when(() -> BasicSshSessionPool.create(anyString(), anyString(), anyString(), anyInt())).thenReturn(sshSessionPool);
        sshSftpConnection = spy(new SshSftpConnection("host", "username", "password", 22));
        when(sshSessionPool.getSession()).thenReturn(sshSession);
        when(sshSession.openChannel(anyString())).thenReturn(channel);
        aopContext.when(AopContext::currentProxy).thenReturn(sshSftpConnection);
    }

    @AfterEach
    void cleanUp() {
        aopContext.close();
        basicSshSessionPoolMockedStatic.close();
    }

    @Test
    void connect() throws Exception {
        doReturn(sshSession).when(sshSessionPool).getSession();
        Session actual = sshSftpConnection.connect();
        verify(sshSession, times(1)).connect();
        assertEquals(sshSession, actual);
    }
}

错误信息 #

Cannot invoke "org.springframework.retry.RetryContext.getRetryCount()" because the return value of "org.springframework.retry.support.RetrySynchronizationManager.getContext()" is null
java.lang.NullPointerException: Cannot invoke "org.springframework.retry.RetryContext.getRetryCount()" because the return value of "org.springframework.retry.support.RetrySynchronizationManager.getContext()" is null
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

解决建议 #

• 确保Spring Retry的AOP代理生效
  当前测试直接调用sshSftpConnection.connect()方法，未通过Spring代理对象触发@Retryable注解的切面，导致RetrySynchronizationManager未初始化上下文。可改用@SpringBootTest加载应用上下文，通过依赖注入获取代理后的Bean调用方法。

• 手动初始化RetryContext（单元测试场景）
  若不想加载完整Spring上下文，可手动创建RetryTemplate执行目标方法，强制初始化重试上下文：

  @Test
  void connectWithRetry() throws Exception {
      RetryTemplate retryTemplate = new RetryTemplate();
      SimpleRetryPolicy retryPolicy = new SimpleRetryPolicy();
      retryPolicy.setMaxAttempts(3); // 替换为测试用的重试次数
      retryTemplate.setRetryPolicy(retryPolicy);
  
      Session actual = retryTemplate.execute(context -> {
          // 手动同步重试计数到目标对象
          Field retryCountField = SshSftpConnection.class.getDeclaredField("retryCountConnect");
          retryCountField.setAccessible(true);
          retryCountField.set(sshSftpConnection, context.getRetryCount());
          
          return sshSftpConnection.connect();
      });
  
      verify(sshSession, times(1)).connect();
      assertEquals(sshSession, actual);
  }
  

• 增加空指针防护
  在原方法中对RetrySynchronizationManager.getContext()的返回值做空判断，避免测试或异常场景下触发空指针：

  public Session connect() {
      RetryContext context = RetrySynchronizationManager.getContext();
      retryCountConnect = context != null ? context.getRetryCount() : 0;
      // 后续原有逻辑不变
  }
  

• 使用Spring Retry测试支持
  引入spring-retry-test依赖，结合@EnableRetry和测试专用注解，让测试环境自动管理重试上下文。

内容的提问来源于stack exchange，提问作者user2769790