Wiremock: a powerful tool for API testing

I wrote an introduction before HttpClient Two kinds of retrial mechanism of , But we don't know if we will try again as expected .

It's provided to us by others API It's usually normal , Many errors don't recur stably , It also makes it impossible for us to conduct a comprehensive test . It is in this case that , I learned that WireMock.

This article does not intend to do an introductory tutorial , The point is how to use WireMock Solve practical problems .

Initialize the caller

First, initialize a HttpClient

public ZwroksApi(){
    RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(1000).build();
    DefaultServiceUnavailableRetryStrategy serviceUnavailableRetryStrategy = new DefaultServiceUnavailableRetryStrategy();
    httpClient = HttpClients.custom()
        .setServiceUnavailableRetryStrategy(serviceUnavailableRetryStrategy)
        .setDefaultRequestConfig(requestConfig)
        .build();
}

The configuration is as follows

1. Exception retries are enabled by default , retry 3 Time .
2. Using the default service unavailable retry policy , Will try again 1 Time , interval 1 second .
3. Set up SocketTimeout by 1 second , Used to simulate timeout .

Exception retry

Overtime

First, let's simulate the timeout , Set fixed delay 2 second , So it's going to be overtime , Try again as expected 3 Time , So it's a request 4 Time .

@Test
public void testSocketTimeOut() {
    stubFor(get(urlEqualTo("/test"))
            .willReturn(aResponse()
                        .withStatus(HttpStatus.SC_OK)
                        .withHeader("Content-Type", "text/xml")
                        .withBody("ok")
                        .withFixedDelay(2000)));
    zwroksApi.test();
    verify(4, getRequestedFor(urlEqualTo("/test")));
}

But the result

Expected exactly 4 requests matching the following pattern but received 1

The specific reason has been mentioned in the previous article ,SocketTimeoutException yes InterruptedIOException Subclasses of , Won't try again .

How to time out and try again , It was also mentioned in the last article , I won't repeat it here .

Erroneous return

WireMock Several error returns are provided in , It's also easy to use

@Test
public void testBadResponse() {
    stubFor(get(urlEqualTo("/test"))
            .willReturn(aResponse().withFault(Fault.CONNECTION_RESET_BY_PEER)));
    zwroksApi.test();
    verify(4, getRequestedFor(urlEqualTo("/test")));
}

It's a mistake at runtime java.net.SocketException: Connection reset, This kind of exception will happen , So here the test can pass .

Service unavailable, try again

The code called is as follows , I hope to return to 503 Try again

@Test
public void testServiceUnavailable() {
    stubFor(get(urlEqualTo("/test"))
            .willReturn(aResponse()
                        .withStatus(HttpStatus.SC_SERVICE_UNAVAILABLE)
                        .withHeader("Content-Type", "text/xml")
                        .withBody("service unavailable")));
    zwroksApi.test();
    verify(2, getRequestedFor(urlEqualTo("/test")));
}

The test here can also pass .WireMock Provides the ability to get request logs , Except for the times , We can see if the two requests are one second apart .

    List<ServeEvent> allServeEvents = getAllServeEvents();
    long firstTime = allServeEvents.get(1).getRequest().getLoggedDate().getTime();
    long lastTime = allServeEvents.get(0).getRequest().getLoggedDate().getTime();
    assert lastTime - firstTime > 1000;

Here's just a small part of WireMock The function of , More functions can go to the official website to see the document , Very easy to understand .