Spock Mock在Lambda函数中失效问题求助

问题场景 #

我尝试用Spock Mock RestTemplateAdapter，但在Lambda函数内部的CompletableFuture中无法正常生效。将retrieveProductListResponse改为public并直接从测试中调用时，Spock Mock能正常工作，因此怀疑问题与CompletableFuture内的Lambda执行有关。我已经把RestTemplate封装到适配器接口中，但问题依然存在。

测试代码 #

RestTemplateAdapter restTemplateAdapter = Mock(RestTemplateAdapter)
int maxRety = 5
String baseUrl = "baseUrl"
ProductRequestPort productRequestPort = new ProductRequestAdapter( restTemplateAdapter, baseUrl, maxRety)

def "should throw error"() {
    given:
    String errorMsg = "Error test message"
    Long customerCode = 1234L

    when:
    productRequestPort.find(customerCode)
    then:

    maxRety * restTemplateAdapter.exchange(_, _, _, _) >> { throw new RuntimeException(errorMsg) }
    GatewayException error = thrown(GatewayException.class)
    error.getMessage() == "Error when trying to get products."
}

待Mock的方法实现 #

public CompletableFuture<ProductListResponse> find(Long customerCode) {
    String url = BASE_URL + customerCode;
    HttpEntity<?> entity = new HttpEntity<>();

    return CompletableFuture.supplyAsync(() -> {
        return retrieveProductListResponse(customerCode, url, entity);
    });
}

private ProductListResponse retrieveProductListResponse(Long customerCode, String url, HttpEntity<?> entity) {
    int attempt = 0;
    while (attempt < MAX_RETRIES) {
        try {
            ResponseEntity<ProductListResponse> response = restTemplateAdapter.exchange(
                    url,
                    HttpMethod.GET,
                    entity,
                    ProductListResponse.class
            );
            return response.getBody();
        } catch (Exception e) {
            attempt++;
        }
    }
    throw new GatewayException(ERROR_GETTING_PRODUCTS);
}

测试报错信息 #

Too few invocations for:

maxRety * restTemplateAdapter.exchange(_, _, _, _) >> { throw new RuntimeException(errorMsg) }   (1 invocation)

同时Mock的restTemplateAdapter返回null响应。

内容的提问来源于stack exchange，提问作者Myphre