The JUnit 4.x Rule

The JUnit rule provides a convenient way to include WireMock in your test cases. It handles the lifecycle for you, starting the server before each test method and stopping afterwards.

Basic usage

To make WireMock available to your tests on its default port (8080):

@Rule
public WireMockRule wireMockRule = new WireMockRule();

The rule’s constructor can take an Options instance to override various settings. An Options implementation can be created via the WireMockConfiguration.options() builder:

@Rule
public WireMockRule wireMockRule = new WireMockRule(options().port(8888).httpsPort(8889));

See Configuration for details.

Unmatched requests

The JUnit rule will verify that all requests received during the course of a test case are served by a configured stub, rather than the default 404. If any are not a VerificationException is thrown, failing the test. This behaviour can be disabled by passing an extra constructor flag:

@Rule
public WireMockRule wireMockRule = new WireMockRule(options().port(8888), false);

Other @Rule configurations

With a bit more effort you can make the WireMock server continue to run between test cases. This is easiest in JUnit 4.10:

@ClassRule
@Rule
public static WireMockClassRule wireMockRule = new WireMockClassRule(8089);

Unfortunately JUnit 4.11 and above prohibits @Rule on static members so a slightly more verbose form is required:

@ClassRule
public static WireMockClassRule wireMockRule = new WireMockClassRule(8089);

@Rule
public WireMockClassRule instanceRule = wireMockRule;

Accessing the stubbing and verification DSL from the rule

In addition the the static methods on the WireMock class, it is also possible to configure stubs etc. via the rule object directly. There are two advantages to this - 1) it’s a bit faster as it avoids sending commands over HTTP, and 2) if you want to mock multiple services you can declare a rule per service but not have to create a client object for each e.g.

@Rule
public WireMockRule service1 = new WireMockRule(8081);

@Rule
public WireMockRule service2 = new WireMockRule(8082);

@Test
public void bothServicesDoStuff() {
    service1.stubFor(get(urlEqualTo("/blah")).....);
    service2.stubFor(post(urlEqualTo("/blap")).....);

    ...
}