bjerat

class InventoryClientTest {

    private InventoryClient cut;

    public static MockWebServer mockBackEnd;

    @BeforeAll
    public static void setUp() throws IOException {
        mockBackEnd = new MockWebServer();
        mockBackEnd.start();

bjerat

@GetExchange
List<CharacterResponse> getByName(@RequestParam String lastName);

// vs.

public List<CharacterResponse> getByName(String lastName) {
    return webClient
            .get()
            .uri(uriBuilder -> uriBuilder
                    .path("/characters")

bjerat

CharacterResponse brandon = characterClient.addCharacter(new AddCharacterRequest("Brandon", "Stark"));

List<CharacterResponse> starks = characterClient.getByName("Stark");

Optional<CharacterResponse> eddardStark = characterClient.getById(1);

Optional<CharacterResponse> unknown = characterClient.getById(1337L); // empty

characterClient.deleteById(brandon.id());

bjerat

@Configuration
public class CharacterClientConfig {

    @Bean
    public CharacterClient characterClient(CharacterClientProperties properties) {
        WebClient webClient = WebClient.builder()
                .baseUrl(properties.getUrl())
                .defaultStatusHandler(
                        httpStatusCode -> HttpStatus.NOT_FOUND == httpStatusCode,
                        response -> Mono.empty())

bjerat

@HttpExchange(
        url = "/characters",
        accept = MediaType.APPLICATION_JSON_VALUE)
public interface CharacterClient {

    @GetExchange
    List<CharacterResponse> getByName(@RequestParam String lastName);

    @GetExchange("/{id}")
    Optional<CharacterResponse> getById(@PathVariable long id);

bjerat

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

bjerat

Mono<InventoryEntry> result = cut.getByName(expectedEntry.name());

StepVerifier
    .withVirtualTime(() -> result)
    // ...

bjerat

retrySpec = Retry.backoff(
    inventoryClientProperties.getRetry().getMaxAttempts(),
    inventoryClientProperties.getRetry().getBackoffDuration()
)

bjerat

@Test
public void verifyGetByNameRecoversFromServerFailuresWithVirtualTime() {
    InventoryEntry expectedEntry = new InventoryEntry(42, "Der lange Weg zu einem kleinen zornigen Planeten", 5);

    mockBackEnd.enqueue(assembleResponseWithStatusCode(500));
    mockBackEnd.enqueue(assembleResponse(expectedEntry));

    StepVerifier
            .withVirtualTime(() -> cut.getByName(expectedEntry.name()))
            .expectSubscription()

bjerat

@Test
public void verifyGetByNameRecoversFromServerFailuresWithBlock() {
    InventoryEntry expectedEntry = new InventoryEntry(42, "Der lange Weg zu einem kleinen zornigen Planeten", 5);

    mockBackEnd.enqueue(assembleResponseWithStatusCode(500));
    mockBackEnd.enqueue(assembleResponse(expectedEntry));

    InventoryEntry actualEntry = cut
            .getByName(expectedEntry.name())
            .block();