pact-jvm-consumer-junit5

JUnit 5 support for Pact consumer tests

Dependency

The library is available on maven central using:

• group-id = au.com.dius.pact.consumer
• artifact-id = junit5
• version-id = 4.4.X

Usage

1. Add the Pact consumer test extension to the test class.

To write Pact consumer tests with JUnit 5, you need to add @PactConsumerTest to your test class. This replaces the PactRunner used for JUnit 4 tests. The rest of the test follows a similar pattern as for JUnit 4 tests.

@PactConsumerTest
class ExampleJavaConsumerPactTest {

Alternatively, you can explicitly declare the JUnit extension.

@ExtendWith(PactConsumerTestExt.class)
class ExampleJavaConsumerPactTest {

2. create a method annotated with @Pact that returns the interactions for the test

For each test (as with JUnit 4), you need to define a method annotated with the @Pact annotation that returns the interactions for the test.

    @Pact(provider="ArticlesProvider", consumer="test_consumer")
    public RequestResponsePact createPact(PactDslWithProvider builder) {
        return builder
            .given("test state")
            .uponReceiving("ExampleJavaConsumerPactTest test interaction")
                .path("/articles.json")
                .method("GET")
            .willRespondWith()
                .status(200)
                .body("{\"responsetest\": true}")
            .toPact();
    }

Note for V4 Pacts, the format of the method needs to be

    @Pact(provider="ArticlesProvider", consumer="test_consumer")
    public V4Pact createPact(PactDslWithProvider builder) {
        return builder
            .given("test state")
            .uponReceiving("ExampleJavaConsumerPactTest test interaction")
                .path("/articles.json")
                .method("GET")
            .willRespondWith()
                .status(200)
                .body("{\"responsetest\": true}")
            .toPact(V4Pact.class);
    }

3. Link the mock server with the interactions for the test with @PactTestFor

Then the final step is to use the @PactTestFor annotation to tell the Pact extension how to setup the Pact test. You can either put this annotation on the test class, or on the test method. For examples see ArticlesTest and MultiTest.

The @PactTestFor annotation allows you to control the mock server in the same way as the JUnit 4 PactProviderRule. It allows you to set the hostname to bind to (default is localhost) and the port (default is to use a random port). You can also set the Pact specification version to use (default is V3).

@PactConsumerTest
@PactTestFor(providerName = "ArticlesProvider")
public class ExampleJavaConsumerPactTest {

NOTE on the hostname: The mock server runs in the same JVM as the test, so the only valid values for hostname are:

hostname	result
localhost	binds to the address that localhost points to (normally the loopback adapter)
127.0.0.1 or ::1	binds to the loopback adapter
host name	binds to the default interface that the host machines DNS name resolves to
0.0.0.0 or ::	binds to the all interfaces on the host machine

Matching the interactions by provider name

If you set the providerName on the @PactTestFor annotation, then the first method with a @Pact annotation with the same provider name will be used. See ArticlesTest for an example.

Matching the interactions by method name

If you set the pactMethod on the @PactTestFor annotation, then the method with the provided name will be used (it still needs a @Pact annotation). See MultiTest for an example.

Injecting the mock server into the test

You can get the mock server injected into the test method by adding a MockServer parameter to the test method.

  @Test
  void test(MockServer mockServer) throws IOException {
    HttpResponse httpResponse = Request.Get(mockServer.getUrl() + "/articles.json").execute().returnResponse();
    assertThat(httpResponse.getStatusLine().getStatusCode(), is(equalTo(200)));
  }

This helps with getting the base URL of the mock server, especially when a random port is used.

Changing the directory pact files are written to

By default, pact files are written to target/pacts (or build/pacts if you use Gradle), but this can be overwritten with the pact.rootDir system property. This property needs to be set on the test JVM as most build tools will fork a new JVM to run the tests.

For Gradle, add this to your build.gradle:

test {
    systemProperties['pact.rootDir'] = "$buildDir/custom-pacts-directory"
}

For maven, use the systemPropertyVariables configuration:

<project>
  [...]
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>2.18</version>
        <configuration>
          <systemPropertyVariables>
            <pact.rootDir>some/other/directory</pact.rootDir>
            <buildDirectory>${project.build.directory}</buildDirectory>
            [...]
          </systemPropertyVariables>
        </configuration>
      </plugin>
    </plugins>
  </build>
  [...]
</project>

For SBT:

fork in Test := true,
javaOptions in Test := Seq("-Dpact.rootDir=some/other/directory")

Using @PactDirectory annotation

You can override the directory the pacts are written in a test by adding the @PactDirectory annotation to the test class.

Forcing pact files to be overwritten

By default, when the pact file is written, it will be merged with any existing pact file. To force the file to be overwritten, set the Java system property pact.writer.overwrite to true.

Having values injected from provider state callbacks

You can have values from the provider state callbacks be injected into most places (paths, query parameters, headers, bodies, etc.). This works by using the V3 spec generators with provider state callbacks that return values. One example of where this would be useful is API calls that require an ID which would be auto-generated by the database on the provider side, so there is no way to know what the ID would be beforehand.

The following DSL methods allow you to set an expression that will be parsed with the values returned from the provider states:

For JSON bodies, use valueFromProviderState.
For headers, use headerFromProviderState.
For query parameters, use queryParameterFromProviderState.
For paths, use pathFromProviderState.

For example, assume that an API call is made to get the details of a user by ID. A provider state can be defined that specifies that the user must exist, but the ID will be created when the user is created. So we can then define an expression for the path where the ID will be replaced with the value returned from the provider state callback.

    .pathFromProviderState("/api/users/${id}", "/api/users/100")

You can also just use the key instead of an expression:

    .valueFromProviderState('userId', 'userId', 100) // will lookup value using userId as the key

Overriding the expression markers ${ and } (4.1.25+)

You can change the markers of the expressions using the following system properties:

• pact.expressions.start (default is ${)
• pact.expressions.end (default is })

Using HTTPS

You can enable a HTTPS mock server by setting https=true on the @PactTestFor annotation. Note that this mock server will use a self-signed certificate, so any client code will need to accept self-signed certificates.

Using own KeyStore

You can provide your own KeyStore file to be loaded on the MockServer. In order to do so you should fulfill the properties keyStorePath, keyStoreAlias, keyStorePassword, privateKeyPassword on the @PactTestFor annotation. Please bear in mind you should also enable HTTPS flag.

Using multiple providers in a test (4.2.5+)

It is advisable to focus on a single interaction with each test, but you can enable multiple providers in a single test. In this case, a separate mock server will be started for each configured provider.

To enable this:

1. Create a method to create the Pact for each provider annotated with the @Pact(provider = "....") annotation. The provider name must be set on the annotation. You can create as many of these as required, but each must have a unique provider name.
2. In the test method, use the pactMethods attribute on the @PactTestFor annotation with the names of all the methods defined in step 1.
3. Add a MockServer parameter to the test method for each provider configured in step 1 with a @ForProvider annotation with the name of the provider.
4. In your test method, interact with each of the mock servers passed in step 3. Note that if any mock server does not get the requests it expects, it will fail the test.

For an example, see MultiProviderTest.

Dealing with persistent HTTP/1.1 connections (Keep Alive)

As each test will get a new mock server, connections can not be persisted between tests. HTTP clients can cache connections with HTTP/1.1, and this can cause subsequent tests to fail. See #342 and #1383.

One option (if the HTTP client supports it, Apache HTTP Client does) is to set the system property http.keepAlive to false in the test JVM. The other option is to set pact.mockserver.addCloseHeader to true to force the mock server to send a Connection: close header with every response (supported with Pact-JVM 4.2.7+).

Testing messages

You can use Pact to test interactions with messaging systems. There are two main types of message support: asynchronous messages and synchronous request/response messages.

Asynchronous messages

Asynchronous messages are your normal type of single shot or fire and forget type messages. They are typically sent to a message queue or topic as a notification or event. With Pact tests, we will be testing that our consumer of the messages works with the messages setup as the expectations in test. This should be the message handler code that processes the actual messages that come off the message queue in production.

For example:

builder.given("Some Provider State")
    .expectsToReceive("a test message")
    .withContent("{\"value\": \"test\"}")
    .toPact();

or using a Dsl object:

builder.given("Some Provider State")
    .expectsToReceive("a test message")
    .withContent(new PactDslJsonBody()
      .stringValue("testParam1", "value1")
      .stringValue("testParam2", "value2"))
    .toPact();

You can use either the V3 Message Pact or the V4 Asynchronous Message interaction to test these types of interactions.

For a V3 message pact example, see AsyncMessageTest.

For a V4 asynchronous message example, see V4AsyncMessageTest.

Matching message metadata

You can also use matching rules for the metadata associated with the message. There is a MetadataBuilder class to help with this. You can access it via the withMetadata method that takes a Java Consumer on the MessagePactBuilder class.

For example:

builder.given("SomeProviderState")
    .expectsToReceive("a test message with metadata")
    .withMetadata(md -> {
        md.add("metadata1", "metadataValue1");
        md.add("metadata2", "metadataValue2");
        md.add("metadata3", 10L);
        md.matchRegex("partitionKey", "[A-Z]{3}\\d{2}", "ABC01");
    })
    .withContent("{\"value\": \"test\"}")
    .toPact();

V4 Synchronous request/response messages

Synchronous request/response messages are a form of message interchange were a request message is sent to another service and one or more response messages are returned. Examples of this would be things like Websockets and gRPC.

For a V4 synchronous request/response message example, see V4AsyncMessageTest.

Using Pact plugins (version 4.3.0+)

The PactBuilder consumer test builder supports using Pact plugins. Plugins are defined in the Pact plugins project. To use plugins requires the use of Pact specification V4 Pacts.

To use a plugin, first you need to let the builder know to load the plugin (using the usingPlugin method) and then configure the interaction based on the requirements for the plugin. Each plugin may have different requirements, so you will have to consult the plugin docs on what is required. 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.

Then you need to use the with method that takes a Map-based data structure and passed it on to the plugin to setup the interaction.

For example, if we use the CSV plugin from the plugins project, our test would look like:

@PactConsumerTest
class CsvClientTest {
  /**
   * Setup an interaction that makes a request for a CSV report 
   */
  @Pact(consumer = "CsvClient")
  V4Pact pact(PactBuilder builder) {
    return builder
      // Tell the builder to load the CSV plugin
      .usingPlugin("csv")
      // Interaction we are expecting to receive
      .expectsToReceive("request for a report", "core/interaction/http")
      // Data for the interaction. This will be sent to the plugin
      .with(Map.of(
        "request.path", "/reports/report001.csv",
        "response.status", "200",
        "response.contents", Map.of(
          "pact:content-type", "text/csv",
          "csvHeaders", false,
          "column:1", "matching(type,'Name')",
          "column:2", "matching(number,100)",
          "column:3", "matching(datetime, 'yyyy-MM-dd','2000-01-01')"
        )
      ))
      .toPact();
  }

  /**
   * Test to get the CSV report
   */
  @Test
  @PactTestFor(providerName = "CsvServer", pactMethod = "pact")
  void getCsvReport(MockServer mockServer) throws IOException {
    // Setup our CSV client class to point to the Pact mock server
    CsvClient client = new CsvClient(mockServer.getUrl());
    
    // Fetch the CSV report
    List<CSVRecord> csvData = client.fetch("report001.csv", false);
    
    // Verify it is as expected
    assertThat(csvData.size(), is(1));
    assertThat(csvData.get(0).get(0), is(equalTo("Name")));
    assertThat(csvData.get(0).get(1), is(equalTo("100")));
    assertThat(csvData.get(0).get(2), matchesRegex("\\d{4}-\\d{2}-\\d{2}"));
  }
}

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'.

Mixing Pact and non-Pact test methods in the same test class

By default, the Pact lifecycle will be invoked for every test method and will expect there to be a method annotated with @Pact for each test method invoked. To add non-Pact tests, just annotate the non-Pact test method with the @PactIgnore annotation.