Using WireMock with Pact

WireMock Pact

WireMock Pact will get the requests from WireMock and create Pact JSON files on the filesystem. The Pact JSON can be published to a Pactflow broker.

WireMock Pact contains:

• wiremock-pact-lib - A library that can transform WireMock ServeEvent:s to Pact JSON.
• wiremock-pact-extension-junit5 - A WireMock extension, and JUnit 5, that is intended to ease usage of the library.
• wiremock-pact-example-springboot-app - A SpringBoot application that shows how it can be used.

WireMock Pact is released to Maven Central. And available on GitHub.

Usage - Junit 5

The extension is both a WireMock extension and a JUnit 5 extension. When using wiremock-spring-boot it can be configured like this in a base class of your tests:

import com.github.tomakehurst.wiremock.core.WireMockConfiguration;
import com.maciejwalkowiak.wiremock.spring.ConfigureWireMock;
import com.maciejwalkowiak.wiremock.spring.EnableWireMock;
import com.maciejwalkowiak.wiremock.spring.WireMockConfigurationCustomizer;
import org.junit.jupiter.api.extension.RegisterExtension;
import se.bjurr.wiremockpact.wiremockpactextensionjunit5.WireMockPactExtension;
import se.bjurr.wiremockpact.wiremockpactlib.api.WireMockPactConfig;

@EnableWireMock({
  @ConfigureWireMock(
      name = "wiremock-service-name",
      property = "wiremock.server.url",
      stubLocation = "wiremock",
      configurationCustomizers = {WireMockPactBaseTest.class})
})
public class WireMockPactBaseTest implements WireMockConfigurationCustomizer {
  @RegisterExtension
  static WireMockPactExtension WIREMOCK_PACT_EXTENSION =
      new WireMockPactExtension(
          WireMockPactConfig.builder() //
              .setConsumerDefaultValue("WireMockPactExample") //
              .setProviderDefaultValue("UnknownProvider") //
              .setPactJsonFolder("src/test/resources/pact-json"));

  @Override
  public void customize(
      final WireMockConfiguration configuration, final ConfigureWireMock options) {
    configuration.extensions(WIREMOCK_PACT_EXTENSION);
  }
}

Usage - Library

It can be used as a library.

public class ExampleTest {
  private static WireMockServer server;
  private static WireMockPactApi wireMockPactApi;

  @BeforeAll
  public static void beforeEach() throws IOException {
    server = new WireMockServer();
    server.start();

    stubFor(
        post(anyUrl())
            .willReturn(
                ok()
                .withHeader("content-type", "application/json")
                .withBody("""
                {"a":"b"}
                """))
            .withMetadata(
                new Metadata(
                    Map.of(
                        WireMockPactMetadata.METADATA_ATTR,
                        new WireMockPactMetadata()
                            .setProvider("some-specific-provider")))));

    wireMockPactApi =
        WireMockPactApi.create(
            new WireMockPactConfig()
                .setConsumerDefaultValue("my-service")
                .setProviderDefaultValue("unknown-service")
                .setPactJsonFolder("the/pact-json/folder"));
    wireMockPactApi.clearAllSaved();
  }

  @Test
  public void testInvoke() {
    // Do stuff that invokes WireMock...
  }

  @AfterAll
  public static void after() {
    for (final ServeEvent serveEvent : server.getAllServeEvents()) {
      wireMockPactApi.addServeEvent(serveEvent);
    }
    // Save pact-json to folder given in WireMockPactApi
    wireMockPactApi.saveAll();
    server.stop();
  }
}

Mappings metadata - Set provider in mapping

You can adjust any mappings file like this to specify the provider of a mapping in its metadata field:

{
  "id" : "d68fb4e2-48ed-40d2-bc73-0a18f54f3ece",
  "request" : {
    "urlPattern" : "/animals/1",
    "method" : "GET"
  },
  "response" : {
    "status" : 202
  },
  "uuid" : "d68fb4e2-48ed-40d2-bc73-0a18f54f3ece",
  "metadata": {
   "wireMockPactSettings": {
     "provider":"some-other-system"
   }
  }
}

Or programmatically:

    stubFor(
        post(anyUrl())
            .withMetadata(
                new Metadata(
                    Map.of(
                        WireMockPactMetadata.METADATA_ATTR,
                        new WireMockPactMetadata()
                            .setProvider("some-specific-provider")))));

Publishing to Pact broker

Pact has a CLI tool that can be used for publishing the contracts. But it requires Ruby or Docker. If you don’t have that, perhaps curl is an option. There is a shell script here that can also be used via NPM.

You may want to use something like git-changelog-command-line to get the next version.

There is a test-server at https://test.pactflow.io/ that can be accessed with user dXfltyFMgNOFZAxr8io9wJ37iUpY42M and password O5AIZWxelWbLvqMd8PkAVycBJh2Psyg1.

current_version=$(npx git-changelog-command-line \
  --patch-version-pattern "^fix.*" \
  --print-current-version)
git_hash=`git rev-parse --short HEAD`
participant_version_number="$current_version-$git_hash"

npx pactflow-publish-sh \
 --username=dXfltyFMgNOFZAxr8io9wJ37iUpY42M \
 --password=O5AIZWxelWbLvqMd8PkAVycBJh2Psyg1 \
 --pactflow-broker-url=https://test.pactflow.io/contracts/publish \
 --build-url=http://whatever/ \
 --pact-json-folder=wiremock-pact-example-springboot-app/src/test/resources/pact-json \
 --participant-version-number=$participant_version_number

Useful pages

• WireMock on Java and JVM - Most of JVM generic solutions are applicable to Spring Boot development too