How to start with PACT contract testing in java for a newbie - pact

Question

I have to do a POC on contract testing using pact, but I couldn't found anything helpful for a newbie. Can someone help me with the working code, how to install, execute I will be grateful.

Answer 1

I tried to explain below.
Consumer: Contract created by consumer.
Provider: Contracts tested by provider.
Pack Broker: After contracts are created under location (like targer/pacts) defined by you, you must publish the contracts to the common platform where consumer and provider will see.
Consumer side - Create contract for provider
public class CreateContractForProvider {
#Rule //Provider, HostInterface and Port defined with #Rule annotation (Used PactProviderRuleMk2)
public PactProviderRuleMk2 pactProviderRuleMk2 = new PactProviderRuleMk2(
// Provider Application Name
"ProviderName",
//Mock Server
"localhost",
8112,
this);
#Pact(consumer = "ConsumerName") // Consumer Application Name (Our application) - Consumer defined with #Pact annotation(
public RequestResponsePact createPact(PactDslWithProvider builder) {
Map<String, String> headers = new HashMap();
headers.put("Content-Type", "application/json"); //Defined headers
//Defined responses with PactDslJsonBody()
DslPart expectedResultBodyWhenGetPayments = new PactDslJsonBody()
.integerType("id",308545)
.integerType("contractNo",854452)
.numberType("amount",3312.5)
.stringType("status","UNPAID")
.asBody();
return builder
.uponReceiving("A request for all payments")
.path("/payments")
.method("GET")
.willRespondWith()
.status(200)
.headers(headers)
.body(expectedResultBodyWhenGetPayments).toPact(); //Response bodyies and headers used in return builder
// We can define more than one endpoint with .uponReceiving or .given
//Then we have to test beacuse contracts are created test stage.
//When we say test with #PactVerification, the server we described above stands up(localhost:8112). İf we get localhost:8112/(definedpathlike/payments) its return expectedResultBodyWhenGetPayments.If the test is successful, the contracts is create.
#Test
#PactVerification()
public void pactVerification() {
int contractNo=((Integer) new ContractTestUtil(pactProviderRuleMk2.getPort()).getContractResponse("/payments","contractNo")).intValue();
assertTrue(contractNo == 854452);
}}
Test Util
public class ContractTestUtil {
int port=8111;
public ContractTestUtil(int port) {
this.port=port;
System.out.println("Custom port "+port);
}
public Object getContractResponse(String path,String object) {
try {
System.setProperty("pact.rootDir", "./target/pacts");
System.setProperty("pact.rootDir", "./target/pacts");
String url=String.format("Http://localhost:%d"+path, port);
System.out.println("using url: "+url);
HttpResponse httpResponse = Request.Get(url).execute().returnResponse();
String json = EntityUtils.toString(httpResponse.getEntity());
System.out.println("json="+json);
JSONObject jsonObject = new JSONObject(json);
return jsonObject.get(object);
}
catch (Exception e) {
System.out.println("Unable to get object="+e);
return null;
}
}}
Define Pact Broker
The PactBrokerUr lmust be defined before publishing in pom.
<plugin>
<!-- mvn pact:publish -->
<groupId>au.com.dius</groupId>
<artifactId>pact-jvm-provider-maven_2.11</artifactId>
<version>3.5.10</version>
<configuration>
<pactDirectory>./target/pacts</pactDirectory> <!-- Defaults to ${project.build.directory}/pacts -->
<pactBrokerUrl>http://yourmachine:8113</pactBrokerUrl>
<projectVersion>1.1</projectVersion> <!-- Defaults to ${project.version} -->
<trimSnapshot>true</trimSnapshot> <!-- Defaults to false -->
</configuration>
</plugin>
Now, we can publish with pact:puplish command.
Provider Side - Call contracts created by consumer
In this stage you can test with failsafe plugin. Beacuse its integraion test.
#RunWith(PactRunner.class) // Say JUnit to run tests with custom Runner
#Provider("ProviderName")
#Consumer("ConsumerName")// Set up name of tested provider// Provider Application Name
#PactBroker(port = "8113", host = "yourmachine")
public class VerifyContractsWhichCreatedForProviderIT {
private static ConfigurableWebApplicationContext configurableWebApplicationContext;
#BeforeClass
public static void start() {
configurableWebApplicationContext = (ConfigurableWebApplicationContext)
SpringApplication.run(Application.class);
}
#TestTarget // Annotation denotes Target that will be used for tests
public final Target target = new HttpTarget(8080); //Test Target
}
Finally,you can create contrats and verify contrast created for you with clean test pact:publish verify command.