This blog demonstrates how to setup and test webservice client codes written in Spring RestTemplate.
Obtaining the jar
I am using Spring 3.1 here and have to include the jar file from the spring-mvc-test project into the classpath. The project has since been incorporated into Spring 3.2. See the Spring documentation for details. The codes here are tested against Spring 3.1 and spring-mvc-test. The APIs may be somewhat different in Spring 3.2.
Restful webservice client
My webservice client communicates with the server via XML so I setup RestTemplate with JaxB marshaller and unmarshaller as follows:
<bean id="exampleRestClient" > <property name="template" ref="exampleRestTemplate"></property> <property name="baseUrl" value="<server url>"></property> </bean> <!-- RESTful template and related beans --> <bean id="exampleRestTemplate"> <property name="messageConverters"> <list> <ref bean="marshallingHttpMessageConverter"/> </list> </property> </bean> <bean id="marshallingHttpMessageConverter"> <property name="marshaller" ref="jaxb2Marshaller" /> <property name="unmarshaller" ref="jaxb2Marshaller" /> </bean> <bean id="jaxb2Marshaller"> <property name="contextPath"> <value>com.blog.resttemplatetest.jaxb</value> </property> <property name="schema" value="classpath:myschema.xsd"/> </bean>
The webservice client implements the normal CRUD functions by delegating to its RestTemplate bean. I will focus on the put function here and demonstrate how to write unit test for it in next section.
@Component(“exampleRestClient”)
public class ExampleRestClient {
private RestTemplate template;
private String baseUrl; // base url
public ExampleResponse add(final ExampleData resource, final ExampleResponse response) {
return put(baseUrl, resource, response);
}
private ExampleResponse put(final String url, final ExampleData resource, final ExampleResponse response) {
final HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_XML);
final HttpEntity<ExampleData> requestEntity = new HttpEntity<ExampleData>(resource, headers);
final ResponseEntity<ExampleResponse> reponseEntity = template.exchange(url, HttpMethod.PUT, requestEntity,
response.getClass());
return reponseEntity.getBody();
}
// getters and setters
…
Note that instead of using the put() method in RestTemplate, I use its exchange() method in order to get the return response from the web service, as the RestTemplate#put method does not return anything. Both input and output classes ExampleData and ExampleResponse are JAXB objects generated via xjc from the example XML schemamyschema.xsd.
Writing unit test for webservice client
spring-mvc-test provides a mock server class MockRestServiceServer to support client testing. For example, to test the put add method in our ExampleRestClient:
...
import static org.springframework.test.web.client.RequestMatchers.method;
import static org.springframework.test.web.client.RequestMatchers.requestTo;
import static org.springframework.test.web.client.ResponseCreators.withSuccess;
...
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:example-test.xml" })
public class StorefrontRestClientTest {
private MockRestServiceServer mockServer;
@Autowired
private ExampleRestClient service;
@Before
public void setUp() {
mockServer = MockRestServiceServer.createServer(service.getTemplate()); // (1)
}
private String loadXmlFile(final String filename) throws IOException {
// load xml file into String ...
}
@Test
public void testAddReturnCorrectResponse() throws Exception {
final ObjectFactory factory = new ObjectFactory();
final String responseXml = loadXmlFile("/test/expectedResponse.xml");
mockServer.expect(requestTo(service.getBaseUrl()))
.andExpect(method(HttpMethod.PUT))
.andRespond(withSuccess(responseXml, MediaType.APPLICATION_XML)); // (2)
final ExampleData exampleData= factory.createExampleData();
final ExampleResponse response = (ExampleResponse) service.add(exampleData, new ExampleResponse());
assertEquals(200, response.getStatus()); // (3)
assertEquals(12345, response.getID()); // (3)
mockServer.verify(); // (4)
}
...
// file: expectedResponse.xml
<?xml version="1.0" encoding="UTF-8"?>
<tns:exampleResponse xmlns:tns="http://" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.example.com/example example.xsd ">
<tns:status>200</tns:status>
<tns:ID>12345</tns:ID>
</tns:exampleResponse>Note:
- Instantiate mock server with the RestTemplate to be tested
- This sets the expectations on the request and mocks the response to be returned, in this case the Xml string stored in file expectedResponse.xml (above). Note the static imports required at the top of the codes forrequestTo, addExpect and andResponse.
- Junit assertions as would normally included.
- Call verify() method to ensure that expectations are being met.
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