Spring 云合约：在 URL 生成的合约响应中访问主机名和端口

Question

我们正在努力提供具有以下特征的合同：

import org.springframework.cloud.contract.spec.Contract

Contract.make {
    request {
        method(GET())
        url("/v2/entity")
        headers {
            accept(applicationJson())
        }
    }
    response {
        status 200
        body( """
         {
            "saveLink": "http://<requestedHost>:<requestedPort>/v2/entity/save"
          }
        )
    }
}

如果我们的客户端使用 stubrunner 并选择不同的端口，e.q。 9876，"saveLink" 应在响应 URL 中反映此端口。我们找不到一种简单的 API 方法来获取主机和端口信息。 fromRequest() 或 url() 仅 return 请求的相关部分 URL。这个需求有没有API的方法或者简单的解决办法？还有其他建议吗？

Answer 1

首先，我认为您误解了合同测试的概念。我想知道为什么在那里拥有这些具体价值观对你来说至关重要？在合同测试中，您只会对 link 包含 URL 和端口的一些值感兴趣。您甚至不会调用那个 URL。所以很可能你应该在继续之前改变你的方法。

如果您认为这是唯一的解决方法，我会就您如何解决这个问题提出我的意见（尽管我还没有测试过，但看起来应该可行；））。

目前要完成这一切并不容易。一旦这个 https://github.com/spring-cloud/spring-cloud-contract/pull/429 被合并，在即将发布的 Edgware 版本中会更容易。

不过我会想办法解决的。我们要做的是添加一个转换机制，该机制将在从 WireMock 发回之前修改响应负载。我们将需要转换 class 并且我们还需要扩展现有的存根服务机制。

首先，让我们创建一个自定义 WireMock 扩展，它将分析 WireMock 使用的每个映射。我们只想修改其中包含 saveLink 的那个。

class CustomExtension extends ResponseTransformer {

    @Override
    String getName() {
        return "url-transformer";
    }

    /**
     * Transformer that converts the save the way we want it to look like
     */
    @Override
    Response transform(Request request, Response response, FileSource files, Parameters parameters) {
    if (requestRelatedToMyParticularCase(response)) {
      String body = "\"{\"saveLink\" : \"http://"+ url.host + ":" + url.port + "/v2/entity/save\"}\"";
      return new Response(response.getStatus(), response.getStatusMessage(),
                body, response.getHeaders(), response.wasConfigured(), response.getFault(), response.isFromProxy());
    }
    // if it's not related continue as usual
        return response;
    }

  private boolean requestRelatedToMyParticularCase(Response response) {
    // is it related to your particular scenario ?
    return response.bodyAsString.contains("saveLink");
  }

    /**
     * We want to apply this transformation for all mappings
     */
    @Override
    boolean applyGlobally() {
        return true
    }
}

现在，您可以创建一个实现 HttpServerStub 的 class 并按此处所述进行注册 - http://cloud.spring.io/spring-cloud-static/Dalston.SR3/#_custom_stub_runner 。它基本上是 WireMockHttpServerStub 的副本，只是我们手动添加转换器

public class MyCustomWireMockHttpServerStub implements HttpServerStub {

    private static final Logger log = LoggerFactory.getLogger(MyCustomWireMockHttpServerStub.class);
    private static final int INVALID_PORT = -1;

    private WireMockServer wireMockServer;

  @Override
    public HttpServerStub start(int port) {
        this.wireMockServer = new WireMockServer(myConfig().port(port)
                .notifier(new Slf4jNotifier(true)));
        this.wireMockServer.start();
        return this;
    }

    private WireMockConfiguration myConfig() {
        if (ClassUtils.isPresent("org.springframework.cloud.contract.wiremock.WireMockSpring", null)) {
            return WireMockSpring.options()
                    .extensions(responseTransformers());
        }
        return new WireMockConfiguration().extensions(responseTransformers());
    }

    private Extension[] responseTransformers() {
      List<Extension> extensions = new ArrayList<>();
      extensions.add(defaultResponseTemplateTransformer());
      extensions.add(new CustomExtension());
      return extensions.toArray(new Extension[extensions.size()]);
    }

    private ResponseTemplateTransformer defaultResponseTemplateTransformer() {
        return new ResponseTemplateTransformer(false, helpers());
    }

    @Override
    public int port() {
        return isRunning() ? this.wireMockServer.port() : INVALID_PORT;
    }

    @Override
    public boolean isRunning() {
        return this.wireMockServer != null && this.wireMockServer.isRunning();
    }

    @Override
    public HttpServerStub start() {
        if (isRunning()) {
            if (log.isDebugEnabled()) {
                log.debug("The server is already running at port [" + port() + "]");
            }
            return this;
        }
        return start(SocketUtils.findAvailableTcpPort());
    }

    @Override
    public HttpServerStub stop() {
        if (!isRunning()) {
            if (log.isDebugEnabled()) {
                log.debug("Trying to stop a non started server!");
            }
            return this;
        }
        this.wireMockServer.stop();
        return this;
    }

    @Override
    public HttpServerStub registerMappings(Collection<File> stubFiles) {
        if (!isRunning()) {
            throw new IllegalStateException("Server not started!");
        }
        registerStubMappings(stubFiles);
        return this;
    }

    @Override public String registeredMappings() {
        Collection<String> mappings = new ArrayList<>();
        for (StubMapping stubMapping : this.wireMockServer.getStubMappings()) {
            mappings.add(stubMapping.toString());
        }
        return jsonArrayOfMappings(mappings);
    }

    private String jsonArrayOfMappings(Collection<String> mappings) {
        return "[" + StringUtils.collectionToDelimitedString(mappings, ",\n") + "]";
    }

    @Override
    public boolean isAccepted(File file) {
        return file.getName().endsWith(".json");
    }

    StubMapping getMapping(File file) {
        try (InputStream stream = Files.newInputStream(file.toPath())) {
            return StubMapping.buildFrom(
                    StreamUtils.copyToString(stream, Charset.forName("UTF-8")));
        }
        catch (IOException e) {
            throw new IllegalStateException("Cannot read file", e);
        }
    }

    private void registerStubMappings(Collection<File> stubFiles) {
        WireMock wireMock = new WireMock("localhost", port(), "");
        registerDefaultHealthChecks(wireMock);
        registerStubs(stubFiles, wireMock);
    }

    private void registerDefaultHealthChecks(WireMock wireMock) {
        registerHealthCheck(wireMock, "/ping");
        registerHealthCheck(wireMock, "/health");
    }

    private void registerStubs(Collection<File> sortedMappings, WireMock wireMock) {
        for (File mappingDescriptor : sortedMappings) {
            try {
                wireMock.register(getMapping(mappingDescriptor));
                if (log.isDebugEnabled()) {
                    log.debug("Registered stub mappings from [" + mappingDescriptor + "]");
                }
            }
            catch (Exception e) {
                if (log.isDebugEnabled()) {
                    log.debug("Failed to register the stub mapping [" + mappingDescriptor + "]", e);
                }
            }
        }
    }

    private void registerHealthCheck(WireMock wireMock, String url) {
        registerHealthCheck(wireMock, url, "OK");
    }

    private void registerHealthCheck(WireMock wireMock, String url, String body) {
        wireMock.register(
                WireMock.get(WireMock.urlEqualTo(url)).willReturn(WireMock.aResponse().withBody(body).withStatus(200)));
    }
}

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