Pact Junit 5 Extension

Dependency

The library is available on maven central using:

• group-id = au.com.dius.pact.provider
• artifact-id = junit5
• version-id = 4.6.x

Overview

For writing Pact verification tests with JUnit 5, there is an JUnit 5 Invocation Context Provider that you can use with the @TestTemplate annotation. This will generate a test for each interaction found for the pact files for the provider.

To use it, add the @Provider and one of the pact source annotations to your test class (as per a JUnit 4 test), then add a method annotated with @TestTemplate and @ExtendWith(PactVerificationInvocationContextProvider.class) that takes a PactVerificationContext parameter. You will need to call verifyInteraction() on the context parameter in your test template method.

For example:

@Provider("myAwesomeService")
@PactFolder("pacts")
public class ContractVerificationTest {

    @TestTemplate
    @ExtendWith(PactVerificationInvocationContextProvider.class)
    void pactVerificationTestTemplate(PactVerificationContext context) {
      context.verifyInteraction();
    }

}

For details on the provider and pact source annotations, refer to the Pact junit runner docs.

Test target

You can set the test target (the object that defines the target of the test, which should point to your provider) on the PactVerificationContext, but you need to do this in a before test method (annotated with @BeforeEach). There are three main test targets you can use: HttpTestTarget, HttpsTestTarget and MessageTestTarget. There is also a PluginTestTarget for use when the interactions are provided by a plugin.

For example:

  @BeforeEach
  void before(PactVerificationContext context) {
    context.setTarget(HttpTestTarget.fromUrl(new URL(myProviderUrl)));
    // or something like
    // context.setTarget(new HttpTestTarget("localhost", myProviderPort, "/"));
  }

HttpTestTarget

HttpTestTarget accepts the following options:

Option	Type	Default	Description
host	String	localhost	The hostname to use to access the provider
port	Int	8080	The port the provider is running on
path	String	"/"	The base path the provider is mounted on
httpClientFactory	() -> IHttpClientFactory	Default Factory	Callback used to override the HTTP client factory

HttpsTestTarget

HttpsTestTarget accepts the following options:

Option	Type	Default	Description
host	String	localhost	The hostname to use to access the provider
port	Int	8443	The port the provider is running on
path	String	"/"	The base path the provider is mounted on
insecure	Boolean	false	Disables the standard TLS verification used with HTTPS connections
httpClientFactory	() -> IHttpClientFactory	Default Factory	Callback used to override the HTTP client factory

MessageTestTarget

MessageTestTarget accepts the following options:

Option	Type	Default	Description
packagesToScan	List<String>	empty List	The Java packages to scan to find classes with annotated methods. If your methods are on your test class, you don't need to supply a value for this.
classLoader	ClassLoader?	null	Class loader to use to load the classes with annotated methods

!! Important note for Maven users !!

If you use Maven to run your tests, you will have to make sure that the Maven Surefire plugin is at least version 2.22.1 and configured to use an isolated classpath.

For example, configure it by adding the following to your POM:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.22.1</version>
    <configuration>
        <useSystemClassLoader>false</useSystemClassLoader>
    </configuration>
</plugin>

IMPORTANT NOTE!!!: JVM system properties needs to be set on the test JVM if your build is running with Gradle or Maven.

Gradle and Maven do not pass in the system properties in to the test JVM from the command line. The system properties specified on the command line only control the build JVM (the one that runs Gradle or Maven), but the tests will run in a new JVM. See Maven Surefire Using System Properties and Gradle Test docs.

For Message Tests and Spring and Maven

If you are using Spring (or Springboot), and want to have values injected into your test, you need to ensure that the same class loader is used to execute your annotated test method as Spring is using to inject the values. In particular, options like the Maven Surefire plugin's forkCount == 0 can impact this. Either don't supply any packages to scan (this will use the default class loader and the annotated methods have to be on your test class), or you can provide the classloader to use as the second parameter to MessageTestTarget.

Selecting the Pacts to verify with Consumer Version Selectors [4.3.12+]

If you are using a Pact broker to host your Pact files, you can select the Pacts to verify using Consumer Version Selectors. There are a few ways to do this.

Using an annotated method with a builder

You can add a static method to your test class annotated with au.com.dius.pact.provider.junitsupport.loader.PactBrokerConsumerVersionSelectors which returns a SelectorBuilder. The builder will allow you to specify the selectors to use in a type-safe manner.

For example:

    @au.com.dius.pact.provider.junitsupport.loader.PactBrokerConsumerVersionSelectors
    public static SelectorBuilder consumerVersionSelectors() {
      // Select Pacts for consumers deployed to production with branch 'FEAT-123' 
      return new SelectorBuilder()
        .environment('production')
        .branch('FEAT-123');
    }

Or for example where the branch is set with the BRANCH_NAME environment variable:

    @au.com.dius.pact.provider.junitsupport.loader.PactBrokerConsumerVersionSelectors
    public static SelectorBuilder consumerVersionSelectors() {
      // Select Pacts for consumers deployed to production with branch from CI build 
      return new SelectorBuilder()
        .environment('production')
        .branch(System.getenv('BRANCH_NAME'));
    }

The builder has the following methods:

• mainBranch() - The latest version from the main branch of each consumer, as specified by the consumer's mainBranch property.
• branch(name: String, consumer: String? = null, fallback: String? = null) - The latest version from a particular branch of each consumer, or for a particular consumer if the second parameter is provided. If fallback is provided, falling back to the fallback branch if none is found from the specified branch.
• matchingBranch() - The latest version from any branch of the consumer that has the same name as the current branch of the provider. Used for coordinated development between consumer and provider teams using matching feature branch names.
• deployedOrReleased() - All the currently deployed and currently released and supported versions of each consumer.
• matchingBranch() - The latest version from any branch of the consumer that has the same name as the current branch of the provider. Used for coordinated development between consumer and provider teams using matching feature branch names.
• deployedTo(environment: String) - Any versions currently deployed to the specified environment.
• releasedTo(environment: String) - Any versions currently released and supported in the specified environment.
• environment(environment: String) - Any versions currently deployed or released and supported in the specified environment.
• tag(name: String) - All versions with the specified tag. Tags are deprecated in favor of branches.
• latestTag(name: String) - The latest version for each consumer with the specified tag. Tags are deprecated in favor of branches.
• rawSelectorJson(json: String) - You can also provide the raw JSON snippets for selectors.

If you require more control, your selector method can also return a list of au.com.dius.pact.core.pactbroker.ConsumerVersionSelectors instead of the builder class.

Providing the raw Consumer Version Selectors JSON

You can also set the consumer versions selectors as raw JSON with the pactbroker.consumerversionselectors.rawjson JVM system property or environment variable. This will allow you to pass the selectors in from a CI build.

IMPORTANT NOTE: JVM system properties needs to be set on the test JVM if your build is running with Gradle or Maven. Just passing them in on the command line won't work, as they will not be available to the test JVM that is running your test. To set the properties, see Maven Surefire Using System Properties and Gradle Test docs.

Provider State Methods

Provider State Methods work in the same way as with JUnit 4 tests, refer to the Pact junit runner docs.

Using multiple classes for the state change methods

If you have a large number of state change methods, you can split things up by moving them to other classes. You will need to specify the additional classes on the test context in a Before method. Do this with the withStateHandler or setStateHandlers methods. See StateAnnotationsOnAdditionalClassTest for an example.

Modifying the requests before they are sent

Important Note: You should only use this feature for things that can not be persisted in the pact file. By modifying the request, you are potentially modifying the contract from the consumer tests!

NOTE: JUnit 5 tests do not use @TargetRequestFilter

Sometimes you may need to add things to the requests that can't be persisted in a pact file. Examples of these would be authentication tokens, which have a small life span. The Http and Https test targets support injecting the request that will executed into the test template method (of type org.apache.http.HttpRequest for versions 4.2.x and before, org.apache.hc.core5.http.HttpRequest for versions 4.3.0+), while the plugin test target supports injecting the data that will be used to make the request into the test template method (as an instance of au.com.dius.pact.provider.RequestData). You can then add things to the request before calling the verifyInteraction() method.

For example to add a header:

    @TestTemplate
    @ExtendWith(PactVerificationInvocationContextProvider.class)
    void testTemplate(PactVerificationContext context, HttpRequest request) {
      // This will add a header to the request
      request.addHeader("X-Auth-Token", "1234");
      context.verifyInteraction();
    }

Objects that can be injected into the test methods

You can inject the following objects into your test methods (just like the PactVerificationContext). They will be null if injected before the supported phase.

Object	Can be injected from phase	Description
PactVerificationContext	@BeforeEach	The context to use to execute the interaction test
Pact	any	The Pact model for the test
Interaction	any	The Interaction model for the test
HttpRequest	@TestTemplate	The request that is going to be executed (only for HTTP and HTTPS targets)
RequestData	@TestTemplate	The request data that is going to be executed (only for the Plugin target)
ProviderVerifier	@TestTemplate	The verifier instance that is used to verify the interaction

Allowing the test to pass when no pacts are found to verify (version 4.0.7+)

By default, the test will fail with an exception if no pacts were found to verify. This can be overridden by adding the @IgnoreNoPactsToVerify annotation to the test class. For this to work, you test class will need to be able to receive null values for any of the injected parameters.

Overriding the handling of a body data type

NOTE: version 4.1.3+

By default, bodies will be handled based on their content types. For binary contents, the bodies will be base64 encoded when written to the Pact file and then decoded again when the file is loaded. You can change this with an override property: pact.content_type.override.<TYPE>.<SUBTYPE>=text|json|binary. For instance, setting pact.content_type.override.application.pdf=text will treat PDF bodies as a text type and not encode/decode them.

Controlling the generation of diffs

NOTE: version 4.2.7+

When there are mismatches with large bodies the calculation of the diff can take a long time . You can turn off the generation of the diffs with the JVM system property: pact.verifier.generateDiff=true|false|<dataSize>, where dataSize, if specified, must be a valid data size (for instance 100kb or 1mb). This will turn off the diff calculation for payloads that exceed this size.

For instance, setting pact.verifier.generateDiff=false will turn off the generation of diffs for all bodies, while pact.verifier.generateDiff=512kb will only turn off the diffs if the actual or expected body is larger than 512kb.

Publishing verification results to a Pact Broker

For pacts that are loaded from a Pact Broker, the results of running the verification can be published back to the broker against the URL for the pact. You will be able to see the result on the Pact Broker home screen. You need to set the version of the provider that is verified using the pact.provider.version system property.

To enable publishing of results, set the Java system property or environment variable pact.verifier.publishResults to true.

IMPORTANT NOTE!!!: this property needs to be set on the test JVM if your build is running with Gradle or Maven.

Gradle and Maven do not pass in the system properties in to the test JVM from the command line. The system properties specified on the command line only control the build JVM (the one that runs Gradle or Maven), but the tests will run in a new JVM. See Maven Surefire Using System Properties and Gradle Test docs.

Tagging the provider before verification results are published [4.0.1+]

You can have a tag pushed against the provider version before the verification results are published. To do this you need set the pact.provider.tag JVM system property to the tag value.

From 4.1.8+, you can specify multiple tags with a comma separated string for the pact.provider.tag system property.

Setting the provider branch before verification results are published [4.3.0-beta.7+]

Pact Broker version 2.86.0 or later

You can have a branch pushed against the provider version before the verification results are published. To do this you need set the pact.provider.branch JVM system property to the branch value.

Setting the build URL for verification results [4.3.2+]

You can specify a URL to link to your CI build output. To do this you need to set the pact.verifier.buildUrl JVM system property to the URL value.

Pending Pact Support (version 4.1.0 and later)

If your Pact broker supports pending pacts, you can enable support for that by enabling that on your Pact broker annotation or with JVM system properties. You also need to provide the tags that will be published with your provider's verification results. The broker will then label any pacts found that don't have a successful verification result as pending. That way, if they fail verification, the verifier will ignore those failures and not fail the build.

For example, with annotation:

@Provider("Activity Service")
@PactBroker(host = "test.pactflow.io", tags = {"test"}, scheme = "https",
  enablePendingPacts = "true",
  providerTags = "master"
)
public class PactJUnitTest {

You can also use the pactbroker.enablePending and pactbroker.providerTags JVM system properties.

Then any pending pacts will not cause a build failure.

Work In Progress (WIP) Pact Support (version 4.1.5 and later)

WIP pacts work in the same way as with JUnit 4 tests, refer to the Pact junit runner docs.

Verifying V4 Pact files that require plugins (version 4.3.0+)

Pact files that require plugins can be verified with version 4.3.0+. For details on how plugins work, see the Pact plugin project.

Each required plugin is defined in the plugins section in the Pact metadata in the Pact file. The plugins will be loaded from the plugin directory. By default, this is ~/.pact/plugins or the value of the PACT_PLUGIN_DIR environment variable. Each plugin required by the Pact file must be installed there. You will need to follow the installation instructions for each plugin, but the default is to unpack the plugin into a sub-directory <plugin-name>-<plugin-version> (i.e., for the Protobuf plugin 0.0.0 it will be protobuf-0.0.0). The plugin manifest file must be present for the plugin to be able to be loaded.

Note that the request data used to generate the request for verification can be injected into the test template method using the au.com.dius.pact.provider.RequestData type. This can be used to add any required metadata to the request.

Test Analytics

We are tracking anonymous analytics to gather important usage statistics like JVM version and operating system. To disable tracking, set the 'pact_do_not_track' system property or environment variable to 'true'.

Testing message interactions

When testing with message interactions, the default mechanism is to call a method on the test class that will return the actual message to test. This works by adding the @PactVerifyProvider annotation to the method with the description of the message interaction. For asynchronous messages, the function must take no parameters, and return either the message contents or the message contents plus any metadata. For synchronous messages, the method can also take the request message as a parameter.

For example:

  @PactVerifyProvider('an order confirmation message')
  public String verifyMessageForOrder() {
     Order order = new Order();
     order.setId(10000004);
     order.setPrice(BigDecimal.TEN);
     order.setUnits(15);

     ConfirmationKafkaMessage message = new ConfirmationKafkaMessageBuilder()
     .withOrder(order)
     .build()

     return JsonOutput.toJson(message);
  }

Synchronous message example:

    @PactVerifyProvider("a test message")
    public MessageAndMetadata messageRecievedAndCreated(MessageContents requestMessage) {

        var req = MyMessageHandler.getRequest(requestMessage.getContents().valueAsString());
        Message<String> message = MyMessageBuilder.createResponse(req);
        return generateMessageAndMetadata(message);
    }

    private MessageAndMetadata generateMessageAndMetadata(Message<String> message) {
        HashMap<String, Object> metadata = new HashMap<String, Object>();
        message.getHeaders().forEach((k, v) -> metadata.put(k, v));

        return new MessageAndMetadata(message.getPayload().getBytes(), metadata);
    }