spring restdocs webtestclient ignore custom jackson Module

Question

My system

spring-boot-version 2.0.1.RELEASE
spring-Cloud-Version Finchley.M9
java 1.8
org.springframework.boot:spring-boot-starter-webflux
org.javamoney:moneta:1.2.1
org.springframework.restdocs:spring-restdocs-webtestclient

custom SimpleModule

  @Bean
  public SimpleModule moneyModule() {
    return new MoneyModule();
  }

  public MoneyModule() {
      addSerializer(Money.class, new MoneySerializer());
      addValueInstantiator(Money.class, new MoneyInstantiator());
  }

Integration test

@RunWith(SpringRunner.class)
@ActiveProfiles("integTest")
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
public class XxxxHandlerTest{
    @Autowired
  WebTestClient webTestClient;

  @Rule
  public JUnitRestDocumentation restDocumentation = new JUnitRestDocumentation();

  @Autowired
  ApplicationContext context;

  @Before
  public void init() throws Exception {
    this.webTestClient = WebTestClient.bindToApplicationContext(this.context)
        .configureClient()
        .baseUrl("http://local.com.cn")
        .filter(WebTestClientRestDocumentation
            .documentationConfiguration(this.restDocumentation)
            .operationPreprocessors()
            .withResponseDefaults(prettyPrint())
        )
        .build();
  }

  @Test
  public void testStoreVoucher() {
    Operator mockUser = Operator.builder().name("jack").id(ObjectId.get().toString()).build();
    List<AccountingEntry> accountingEntries = Arrays.asList(AccountingEntry.builder()
        .code("12121").summary("receipt").debit(Money.of(100, "CNY"))
        .credit(Money.of(100, "CNY")).build());
    VoucherPost voucherPost = VoucherPost.builder().operator(mockUser)
        .accountingEntries(accountingEntries).build();
    webTestClient.post()
        .uri(mockUrl)
        .body(BodyInserters.fromObject(voucherPost))
        .exchange().expectStatus().isOk();
}

test error

org.springframework.core.codec.DecodingException: JSON decoding error: Cannot construct instance of `org.javamoney.moneta.Money` (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `org.javamoney.moneta.Money` (although at least one Creator exists): cannot deserialize from Object value (no delegate- or property-based Creator)

When I remove the following code，test code is working properly

this.webTestClient = WebTestClient.bindToApplicationContext(this.context)
        .configureClient()
        .baseUrl("http://local.com.cn")
        .filter(WebTestClientRestDocumentation
            .documentationConfiguration(this.restDocumentation)
            .operationPreprocessors()
            .withResponseDefaults(prettyPrint())
        )
        .build();

I guess the webtestclient's configuration has caused it to ignore the custom jackson module, so I would like to know how to solve this problem. Maybe there is no problem at all, but my configuration is wrong. Please give me some advice. Thank you.

If you literally do what you have described (remove the entire initialisation of this.webTestClient) then I would expect a NullPointerException. Can you describe precisely how you've initialized this.webTestClient in the case where the test code is working properly? — Andy Wilkinson
Sorry I didn't describe it clearly.I tried two initialization methods,@Autowired WebTestClient webTestClient and WebTestClient webTestClient; WebTestClient.bindToApplicationContext.... first way, the Money serializer/deserializer all right, but restdocs has error, because it can not find restDocumentation configuration. the second way, restdocs is ok, but Money deserilzer has exception. — Djack

Andy Wilkinson Andy Wilkinson · Accepted Answer · 2018-06-14T09:44:36

As you are using Spring Boot, I'd recommend that you use @AutoConfigureRestDocs rather than manually configuring a WebTestClient to use REST Docs. This is the easiest way to get a WebTestClient that's been configured with a Jackson ObjectMapper that will use your custom module.

To do so, your test class would look something like this:

@RunWith(SpringRunner.class)
@ActiveProfiles("integTest")
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@AutoConfigureRestDocs(uriHost="local.com.cn")
public class XxxxHandlerTest{

    @Autowired
    WebTestClient webTestClient;

    @Test
    public void testStoreVoucher() {
        Operator mockUser = Operator.builder().name("jack").id(ObjectId.get().toString()).build();
        List<AccountingEntry> accountingEntries = Arrays.asList(AccountingEntry.builder()
            .code("12121").summary("receipt").debit(Money.of(100, "CNY"))
            .credit(Money.of(100, "CNY")).build());
        VoucherPost voucherPost = VoucherPost.builder().operator(mockUser)
            .accountingEntries(accountingEntries).build();
        webTestClient.post()
            .uri(mockUrl)
            .body(BodyInserters.fromObject(voucherPost))
            .exchange().expectStatus().isOk();
    }

}