rest-contract

Reference: Rest-Contract
Reference: Spring Cloud Contract

preface

The main goal of this project is to show how to create a Spring REST application with its contract stubs and consuming the contract within an other Spring application.

When trying to test an application that communicates with other services then we could do one of two things:

• deploy all microservices and perform end to end tests,

• mock other microservices in unit / integration tests.

To solve the second issues Spring Cloud Contract Verifier with Stub Runner were created. Their main idea is to give you very fast feedback, without the need to set up the whole world of microservices.

Spring Cloud Contract Verifier features

• Ensure that HTTP / Messaging stubs (used when developing the client) are doing exactly what actual server-side implementation will do.

• Promote acceptance test driven development method and Microservices architectural style.

• Provide a way to publish changes in contracts that are immediately visible on both sides of the communication.

• Generate boilerplate test code used on the server side.

manual

• pom.xml

  <properties>
      <spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
      <spring-cloud-contract.version>2.0.0.RELEASE</spring-cloud-contract.version>
  </properties>
  

  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-contract-verifier</artifactId>
      <scope>test</scope>
  </dependency>
  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-contract-wiremock</artifactId>
      <scope>test</scope>
  </dependency>
  <dependency>
      <groupId>io.rest-assured</groupId>
      <artifactId>spring-mock-mvc</artifactId>
      <version>3.0.0</version>
      <scope>test</scope>
  </dependency>
  

  <dependencyManagement>
      <dependencies>
          <dependency>
              <groupId>org.springframework.cloud</groupId>
              <artifactId>spring-cloud-dependencies</artifactId>
              <version>${spring-cloud.version}</version>
              <type>pom</type>
              <scope>import</scope>
          </dependency>
      </dependencies>
  </dependencyManagement>    
  

Server / Producer side

• Add the base class

  • Groovy
    groovy/service/BaseClass.groovy

    class BaseClass extends Specification {
        void setup() {
            RestAssuredMockMvc.standaloneSetup(new PersonRestController())
    
            Mock(PersonService) {
                findPersonById(1) >> new Person(1, "foo", "bee")
            }
        }
    }
    

    configure plugins:

    <plugin>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-contract-maven-plugin</artifactId>
        <version>${spring-cloud-contract.version}</version>
        <extensions>true</extensions>
        <configuration>
            <baseClassForTests>service.BaseClass</baseClassForTests>
            <testFramework>SPOCK</testFramework>
        </configuration>
    </plugin>
    
    <plugin>
        <groupId>org.codehaus.gmavenplus</groupId>
        <artifactId>gmavenplus-plugin</artifactId>
        <version>1.6.1</version>
        <executions>
            <execution>
                <goals>
                    <goal>compileTests</goal>
                </goals>
            </execution>
        </executions>
        <configuration>
            <testSources>
                <testSource>
                    <directory>${project.basedir}/src/test/groovy</directory>
                    <includes>
                        <include>**/*.groovy</include>
                    </includes>
                </testSource>
                <testSource>
                    <directory>${project.build.directory}/generated-test-sources/contracts</directory>
                    <includes>
                        <include>**/*.groovy</include>
                    </includes>
                </testSource>
            </testSources>
        </configuration>
    </plugin>
    
    <plugin>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>2.22.0</version>
        <configuration>
            <includes>
                <include>**/*Spec.java</include>
            </includes>
        </configuration>
    </plugin>
    

  • JUnit

    @RunWith(SpringRunner.class)
    @SpringBootTest(classes = ServiceApplication.class)
    public abstract class BaseClass {
    
        @Autowired
        PersonRestController personRestController;
    
        @MockBean
        PersonService personService;
    
        @Before
        public void setup() {
            RestAssuredMockMvc.standaloneSetup(personRestController);
    
            Mockito.when(personService.findPersonById(1))
                    .thenReturn(new Person(1, "foo", "bee"));
        }
    
    }
    

    configure plugin:

    <plugin>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-contract-maven-plugin</artifactId>
        <version>${spring-cloud-contract.version}</version>
        <extensions>true</extensions>
        <configuration>
            <baseClassForTests>service.BaseClass</baseClassForTests>
        </configuration>
    </plugin>
    

client

• pom.xml

  <dependency>
  	<groupId>org.springframework.cloud</groupId>
  	<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
  	<scope>test</scope>
  </dependency>
  

• client/ClientApplicationTests

  @RunWith(SpringRunner.class)
  @SpringBootTest
  @AutoConfigureStubRunner(ids = {"com.example:rest-contract-service:0.0.1-SNAPSHOT:stubs:8100"}, 
          stubsMode = StubRunnerProperties.StubsMode.LOCAL)
  public class ClientApplicationTests
  

  Note that we could also load the stub inside the class (without using @AutoConfigureStubRunner):

  @Rule
  public StubRunnerRule stubRunnerRule = new StubRunnerRule()
          .downloadStub("com.example", "rest-contract-service", "0.0.1-SNAPSHOT", "stubs")
          .withPort(8100)
          .stubsMode(StubRunnerProperties.StubsMode.LOCAL);
  

• Remember to put com.example:rest-contract-service:0.0.1-SNAPSHOT-stubs in your .m2 local maven repository under com/example/rest-contract-service/0.0.1-SNAPSHOT.