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pact-jvm-consumer-junit

Provides a DSL and a base test class for use with Junit to build consumer tests.

##Dependency

The library is available on maven central using:

  • group-id = au.com.dius
  • artifact-id = pact-jvm-consumer-junit_2.11
  • version-id = 2.1.x

##Usage

Using the base ConsumerPactTest

To write a pact spec extend ConsumerPactTest. This base class defines the following four methods which must be overridden in your test class.

  • providerName: Returns the name of the API provider that Pact will mock
  • consumerName: Returns the name of the API consumer that we are testing.
  • createFragment: Returns the PactFrament containing the interactions that the test setup using the ConsumerPactBuilder DSL
  • runTest: The actual test run. It receives the URL to the mock server as a parameter.

Here is an example:

import au.com.dius.pact.model.PactFragment;

import java.util.HashMap;
import java.util.Map;

import static org.junit.Assert.assertEquals;

public class ExampleJavaConsumerPactTest extends ConsumerPactTest {

    @Override
    protected PactFragment createFragment(ConsumerPactBuilder.PactDslWithProvider builder) {
        Map<String, String> headers = new HashMap<String, String>();
        headers.put("testreqheader", "testreqheadervalue");

        return builder
            .given("test state") // NOTE: Using provider states are optional, you can leave it out
            .uponReceiving("a request for something")
                .path("/")
                .method("GET")
                .headers(headers)
                .body("{\"test\":true}")
            .willRespondWith()
                .status(200)
                .headers(headers)
                .body("{\"responsetest\":true}").toFragment();
    }


    @Override
    protected String providerName() {
        return "Some Provider";
    }

    @Override
    protected String consumerName() {
        return "Some Consumer";
    }

    @Override
    protected void runTest(String url) {
        try {
            assertEquals(new ProviderClient(url).getSomething(), "{\"responsetest\":true}");
        } catch (Exception e) {
            // NOTE: if you want to see any pact failure, do not throw an exception here. This should be
            // fixed at some point (see Issue #40 https://github.com/DiUS/pact-jvm/issues/40)
            throw new RuntimeException(e);
        }
    }
}

Using the Pact JUnit Rule

Thanks to @warmuuh we have a JUnit rule that simplifies running Pact consumer tests. To use it, create a test class and then add the rule:

1. Add the Pact Rule to your test class.

    @Rule
    public PactRule rule = new PactRule("localhost", 8080, this);

2. Annotate a method with Pact that returns a pact fragment

    @Pact(state="test state", provider="test_provider", consumer="test_consumer")
    public PactFragment createFragment(PactDslWithState builder) {
        return builder
            .uponReceiving("ExampleJavaConsumerPactRuleTest test interaction")
                .path("/")
                .method("GET")
            .willRespondWith()
                .status(200)
                .body("{\"responsetest\": true}")
            .toFragment();
    }

3. Annotate your test method with PactVerification to have it run in the context of a mock server setup with the appropriate pact from step 2

    @Test
    @PactVerification("test state")
    public void runTest() {
        Map expectedResponse = new HashMap();
        expectedResponse.put("responsetest", true);
        assertEquals(new ConsumerClient("http://localhost:8080").get("/"), expectedResponse);
    }

For an example, have a look at ExampleJavaConsumerPactRuleTest

Using the Pact DSL directly

Sometimes it is not convenient to use the ConsumerPactTest as it only allows one test per test class. The DSL can be used directly in this case.

Example:

import au.com.dius.pact.model.MockProviderConfig;
import au.com.dius.pact.model.PactFragment;
import org.junit.Test;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import static org.junit.Assert.assertEquals;

public class PactTest {

    @Test
    public void testPact() {
        PactFragment pactFragment = ConsumerPactBuilder
            .consumer("Some Consumer")
            .hasPactWith("Some Provider")
            .uponReceiving("a request to say Hello")
                .path("/hello")
                .method("POST")
                .body("{\"name\": \"harry\"}")
            .willRespondWith()
                .status(200)
                .body("{\"hello\": \"harry\"}")
                .toFragment();

        MockProviderConfig config = MockProviderConfig.createDefault();
        VerificationResult result = pactFragment.runConsumer(config, new TestRun() {
            @Override
            public void run(MockProviderConfig config) {
                Map expectedResponse = new HashMap();
                expectedResponse.put("hello", "harry");
                try {
                    assertEquals(new ProviderClient(config.url()).hello("{\"name\": \"harry\"}"),
                            expectedResponse);
                } catch (IOException e) {}
            }
        });

        if (result instanceof PactError) {
            throw new RuntimeException(((PactError)result).error());
        }

        assertEquals(ConsumerPactTest.PACT_VERIFIED, result);
    }

}

The Pact JUnit DSL

The DSL has the following pattern:

.consumer("Some Consumer")
.hasPactWith("Some Provider")
.given("a certain state on the provider")
    .uponReceiving("a request for something")
        .path("/hello")
        .method("POST")
        .body("{\"name\": \"harry\"}")
    .willRespondWith()
        .status(200)
        .body("{\"hello\": \"harry\"}")
    .uponReceiving("another request for something")
        .path("/hello")
        .method("POST")
        .body("{\"name\": \"harry\"}")
    .willRespondWith()
        .status(200)
        .body("{\"hello\": \"harry\"}")
    .
    .
    .
.toFragment()

You can define as many interactions as required. Each interaction starts with uponReceiving followed by willRespondWith. The test state setup with given is a mechanism to describe what the state of the provider should be in before the provider is verified. It is only recorded in the consumer tests and used by the provider verification tasks.

Building JSON bodies with PactDslJsonBody DSL

The body method of the ConsumerPactBuilder can accept a PactDslJsonBody, which can construct a JSON body as well as define regex and type matchers.

For example:

PactDslJsonBody body = new PactDslJsonBody()
    .stringType("name")
    .booleanType("happy")
    .hexValue("hexCode")
    .id()
    .ipAddress("localAddress")
    .numberValue("age", 100)
    .timestamp();

Ensuring all items in a list match an example (2.2.0+)

Lots of the time you might not know the number of items that will be in a list, but you want to ensure that the list has a minimum or maximum size and that each item in the list matches a given example. You can do this with the arrayLike, minArrayLike and maxArrayLike functions.

function description
arrayLike Ensure that each item in the list matches the provided example
maxArrayLike Ensure that each item in the list matches the provided example and the list is no bigger than the provided max
minArrayLike Ensure that each item in the list matches the provided example and the list is no smaller than the provided min

For example:

    DslPart body = new PactDslJsonBody()
        .minArrayLike("users")
            .id()
            .stringType("name")
            .closeObject()
        .closeArray();

This will ensure that the users list is never empty and that each user has an identifier that is a number and a name that is a string.

Matching on paths (version 2.1.5+)

You can use regular expressions to match incoming requests. The DSL has a matchPath method for this. You can provide a real path as a second value to use when generating requests, and if you leave it out it will generate a random one from the regular expression.

For example:

  .given("test state")
    .uponReceiving("a test interaction")
        .matchPath("/transaction/[0-9]+") // or .matchPath("/transaction/[0-9]+", "/transaction/1234567890")
        .method("POST")
        .body("{\"name\": \"harry\"}")
    .willRespondWith()
        .status(200)
        .body("{\"hello\": \"harry\"}")

Matching on headers (version 2.2.2+)

You can use regular expressions to match request and response headers. The DSL has a matchHeader method for this. You can provide an example header value to use when generating requests and responses, and if you leave it out it will generate a random one from the regular expression.

For example:

  .given("test state")
    .uponReceiving("a test interaction")
        .path("/hello")
        .method("POST")
        .matchHeader("testreqheader", "test.*value")
        .body("{\"name\": \"harry\"}")
    .willRespondWith()
        .status(200)
        .body("{\"hello\": \"harry\"}")
        .matchHeader("Location", ".*/hello/[0-9]+", "/hello/1234")

Debugging pact failures

When the test runs, Pact will start a mock provider that will listen for requests and match them against the expectations you setup in createFragment. If the request does not match, it will return a 500 error response.

Each request received and the generated response is logged using SLF4J. Just enable debug level logging for au.com.dius.pact.consumer.UnfilteredMockProvider. Most failures tend to be mismatched headers or bodies.

Changing the directory pact files are written to (2.1.9+)

By default, pact files are written to target/pacts, 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/pacts"
}

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")