Custom Matching

If WireMock’s standard set of request matching strategies isn’t sufficient, you can register one or more request matcher classes containing your own logic.

Custom matchers can be attached directly to stubs via the Java API when using the local admin interface (by calling stubFor(...) on WireMockServer or WireMockRule). They can also be added via the extension mechanism and used with individual stubs by referring to them by name as described above for response transformers.

As with response transformers, per stub mapping parameters can be passed to matchers.

To add a matcher directly to a stub mapping:

wireMockServer.stubFor(requestMatching(new RequestMatcherExtension() {
    @Override
    public MatchResult match(Request request, Parameters parameters) {
        return MatchResult.of(request.getBody().length > 2048);
    }
}).willReturn(aResponse().withStatus(422)));

To use it in a verification :

verify(2, requestMadeFor(new ValueMatcher<Request>() {
    @Override
    public MatchResult match(Request request) {
        return MatchResult.of(request.getBody().length > 2048);
    }
}));

In Java 8 and above this can be achieved using a lambda:

wireMockServer.stubFor(requestMatching(request ->
    MatchResult.of(request.getBody().length > 2048)
).willReturn(aResponse().withStatus(422)));

To create a matcher to be referred to by name, create a class extending RequestMatcher and register it as an extension as per the instructions at the top of this page e.g.

public class BodyLengthMatcher extends RequestMatcherExtension {

    @Override
    public String getName() {
        return "body-too-long";
    }

    @Override
    public MatchResult match(Request request, Parameters parameters) {
        int maxLength = parameters.getInt("maxLength");
        return MatchResult.of(request.getBody().length > maxLength);
    }
}

Then define a stub with it:

stubFor(requestMatching("body-too-long", Parameters.one("maxLength", 2048))
        .willReturn(aResponse().withStatus(422)));

{
    "request": {
        "customMatcher": {
            "name": "body-too-long",
            "parameters": {
                "maxLength": 2048
            }
        }
    },
    "response": {
        "status": 422
    }
}

Combining standard and custom request matchers #

An inline custom matcher can be used in combination with standard matchers in the following way:

stubFor(get(urlPathMatching("/the/.*/one"))
        .andMatching(new MyRequestMatcher()) // Will also accept a Java 8+ lambda
        .willReturn(ok()));

Note that inline matchers of this form can only be used from Java, and only when stubFor is being called against a local WireMock server. An exception will be thrown if attempting to use an inline custom matcher against a remote instance.

Custom matchers defined as extensions can also be combined with standard matchers.

stubFor(get(urlPathMatching("/the/.*/one"))
        .andMatching("path-contains-param", Parameters.one("path", "correct"))
        .willReturn(ok()));

{
    "request": {
        "urlPathPattern": "/the/.*/one",
        "method": "GET",
        "customMatcher": {
            "name": "path-contains-param",
            "parameters": {
                "path": "correct"
            }
        }
    },
    "response": {
        "status": 200
    }
}