是否可以使用wiremock工具模拟连接超时？

Question

我知道它可以通过使用withFixedDelay来模拟SocketTimeoutException ，但是ConnectionTimeoutException呢？

Answer 1

Yes it is possible to do this with WireMock by calling addDelayBeforeProcessingRequests(300) against the Java API or posting the following to http://<host>:<port>/__admin/socket-delay :

{ "milliseconds": 300 }

(Obviously replacing 300 with however many milliseconds you'd like to delay by)

Answer 2

It seems that the answer to this question has been "No", since version 2.0.8-beta .

Tom (author of WireMock) explains why in this GitHub issue :

It's basically impossible to reliably force connection timeouts in pure Java at the moment.

It used to be the case that you could inject a delay before calling .accept() on the socket, but that stopped working a while back, I guess due to a change in the implementation internals.

My recommendation at the moment would be to use a tool that works at the level of the network stack. iptables ... -j DROP type commands will do the trick, or if you want a level of automation over this you can use tools such as https://github.com/tomakehurst/saboteur or https://github.com/alexei-led/pumba .

He also goes on to explain that just stopping WireMock doesn't achieve the same thing:

shutting down WireMock won't have the same effect - when a port is not being listened on, you get a TCP RST (reset) packet back, whereas a connection timeout happens when you get nothing back from the server in the timeout window after your initial SYN packet.

Answer 3

Checkout https://github.com/tomakehurst/saboteur which allows you to simulate network issues. Or you can do it your self with iptables.

Answer 4

java.net.ConnectException essentially means that we can not establish network connection to the intended party. Considering that, I just stopped my wiremock instance and it worked fine.

The implementation of my third party api call catches this exception and re-throws HTTP 500 with the error message(that is what i am trying to assert)

    @Before
    public void setUp() {
        wireMock.start();
    }

    @After
    public void clean() {
        wireMock.resetMappings();
    }

    @Test
    public void shouldSimulateConnectionTimeout() {
        //given - STOP THE WIREMOCK
        wireMock.stop();

        //when
        Response response = getTarget("external api URL")
                             .request()
                             .post(entity(event, APPLICATION_JSON_TYPE));

        //then
        assertEquals(500, response.getStatus());
        assertEquals("{\"message\" : \"java.net.ConnectException: Connection refused\"}", response.readEntity(String.class));
    }

Answer 5

When using WireMock.Net , adding a delay is also possible.

Example:

var server = WireMockServer.Start();

// add a delay of 30 seconds for all requests
server.AddRequestProcessingDelay(TimeSpan.FromSeconds(30));

or

var server = WireMockServer.Start();
server
  .Given(Request.Create().WithPath("/slow"))
  .RespondWith(
    Responses.Create()
      .WithStatusCode(200)
      .WithBody(@"{ ""msg"": ""Hello I'm a little bit slow!"" }")
      .WithDelay(TimeSpan.FromSeconds(10)
  )
);