[[resttestclient]] = RestTestClient `RestTestClient` is an HTTP client designed for testing server applications. It wraps Spring's xref:integration/rest-clients.adoc#rest-restclient[`RestClient`] and uses it to perform requests, but exposes a testing facade for verifying responses. `RestTestClient` can be used to perform end-to-end HTTP tests. It can also be used to test Spring MVC applications without a running server via MockMvc. [[resttestclient-setup]] == Setup To set up a `RestTestClient` you need to choose a server setup to bind to. This can be one of several MockMvc setup choices, or a connection to a live server. [[resttestclient-controller-config]] === Bind to Controller This setup allows you to test specific controller(s) via mock request and response objects, without a running server. [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- RestTestClient client = RestTestClient.bindToController(new TestController()).build(); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- val client = RestTestClient.bindToController(TestController()).build() ---- ====== [[resttestclient-context-config]] === Bind to `ApplicationContext` This setup allows you to load Spring configuration with Spring MVC infrastructure and controller declarations and use it to handle requests via mock request and response objects, without a running server. [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- @SpringJUnitConfig(WebConfig.class) // <1> class MyTests { RestTestClient client; @BeforeEach void setUp(ApplicationContext context) { // <2> client = RestTestClient.bindToApplicationContext(context).build(); // <3> } } ---- <1> Specify the configuration to load <2> Inject the configuration <3> Create the `RestTestClient` Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- @SpringJUnitConfig(WebConfig::class) // <1> class MyTests { lateinit var client: RestTestClient @BeforeEach fun setUp(context: ApplicationContext) { // <2> client = RestTestClient.bindToApplicationContext(context).build() // <3> } } ---- <1> Specify the configuration to load <2> Inject the configuration <3> Create the `RestTestClient` ====== [[resttestclient-fn-config]] === Bind to Router Function This setup allows you to test xref:web/webmvc-functional.adoc[functional endpoints] via mock request and response objects, without a running server. [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- RouterFunction route = ... client = RestTestClient.bindToRouterFunction(route).build(); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- val route: RouterFunction<*> = ... val client = RestTestClient.bindToRouterFunction(route).build() ---- ====== [[resttestclient-server-config]] === Bind to Server This setup connects to a running server to perform full, end-to-end HTTP tests: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client = RestTestClient.bindToServer().baseUrl("http://localhost:8080").build(); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client = RestTestClient.bindToServer().baseUrl("http://localhost:8080").build() ---- ====== [[resttestclient-client-config]] === Client Config In addition to the server setup options described earlier, you can also configure client options, including base URL, default headers, client filters, and others. These options are readily available following the initial `bindTo` call, as follows: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client = RestTestClient.bindToController(new TestController()) .baseUrl("/test") .build(); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client = RestTestClient.bindToController(TestController()) .baseUrl("/test") .build() ---- ====== [[resttestclient-tests]] == Writing Tests xref:integration/rest-clients.adoc#rest-restclient[`RestClient`] and `RestTestClient` have the same API up to the point of the call to `exchange()`. After that, `RestTestClient` provides two alternative ways to verify the response: 1. xref:resttestclient-workflow[Built-in Assertions] extend the request workflow with a chain of expectations 2. xref:resttestclient-assertj[AssertJ Integration] to verify the response via `assertThat()` statements [[resttestclient-workflow]] === Built-in Assertions To use the built-in assertions, remain in the workflow after the call to `exchange()`, and use one of the expectation methods. For example: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/1") .accept(MediaType.APPLICATION_JSON) .exchange() .expectStatus().isOk() .expectHeader().contentType(MediaType.APPLICATION_JSON); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/1") .accept(MediaType.APPLICATION_JSON) .exchange() .expectStatus().isOk() .expectHeader().contentType(MediaType.APPLICATION_JSON) ---- ====== If you would like for all expectations to be asserted even if one of them fails, you can use `expectAll(..)` instead of multiple chained `expect*(..)` calls. This feature is similar to the _soft assertions_ support in AssertJ and the `assertAll()` support in JUnit Jupiter. [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/1") .accept(MediaType.APPLICATION_JSON) .exchange() .expectAll( spec -> spec.expectStatus().isOk(), spec -> spec.expectHeader().contentType(MediaType.APPLICATION_JSON) ); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/1") .accept(MediaType.APPLICATION_JSON) .exchange() .expectAll( { spec -> spec.expectStatus().isOk() }, { spec -> spec.expectHeader().contentType(MediaType.APPLICATION_JSON) } ) ---- ====== You can then choose to decode the response body through one of the following: * `expectBody(Class)`: Decode to single object. * `expectBody()`: Decode to `byte[]` for xref:testing/resttestclient.adoc#resttestclient-json[JSON Content] or an empty body. If the built-in assertions are insufficient, you can consume the object instead and perform any other assertions: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/1") .exchange() .expectStatus().isOk() .expectBody(Person.class) .consumeWith(result -> { // custom assertions (for example, AssertJ)... }); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/1") .exchange() .expectStatus().isOk() .expectBody() .consumeWith { // custom assertions (for example, AssertJ)... } ---- ====== Or you can exit the workflow and obtain a `EntityExchangeResult`: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- EntityExchangeResult result = client.get().uri("/persons/1") .exchange() .expectStatus().isOk() .expectBody(Person.class) .returnResult(); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- val result = client.get().uri("/persons/1") .exchange() .expectStatus().isOk .expectBody() .returnResult() ---- ====== TIP: When you need to decode to a target type with generics, look for the overloaded methods that accept {spring-framework-api}/core/ParameterizedTypeReference.html[`ParameterizedTypeReference`] instead of `Class`. [[resttestclient-no-content]] ==== No Content If the response is not expected to have content, you can assert that as follows: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client.post().uri("/persons") .body(person) .exchange() .expectStatus().isCreated() .expectBody().isEmpty(); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client.post().uri("/persons") .body(person) .exchange() .expectStatus().isCreated() .expectBody().isEmpty() ---- ====== If you want to ignore the response content, the following releases the content without any assertions: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/123") .exchange() .expectStatus().isNotFound() .expectBody(Void.class); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/123") .exchange() .expectStatus().isNotFound .expectBody() ---- ====== [[resttestclient-json]] ==== JSON Content You can use `expectBody()` without a target type to perform assertions on the raw content rather than through higher level Object(s). To verify the full JSON content with https://jsonassert.skyscreamer.org[JSONAssert]: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/1") .exchange() .expectStatus().isOk() .expectBody() .json("{\"name\":\"Jane\"}") ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons/1") .exchange() .expectStatus().isOk() .expectBody() .json("{\"name\":\"Jane\"}") ---- ====== To verify JSON content with https://github.com/jayway/JsonPath[JSONPath]: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons") .exchange() .expectStatus().isOk() .expectBody() .jsonPath("$[0].name").isEqualTo("Jane") .jsonPath("$[1].name").isEqualTo("Jason"); ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- client.get().uri("/persons") .exchange() .expectStatus().isOk() .expectBody() .jsonPath("$[0].name").isEqualTo("Jane") .jsonPath("$[1].name").isEqualTo("Jason") ---- ====== [[resttestclient-assertj]] === AssertJ Integration `RestTestClientResponse` is the main entry point for the AssertJ integration. It is an `AssertProvider` that wraps the `ResponseSpec` of an exchange in order to enable use of `assertThat()` statements. For example: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- ResponseSpec spec = client.get().uri("/persons").exchange(); RestTestClientResponse response = RestTestClientResponse.from(spec); assertThat(response).hasStatusOk(); assertThat(response).hasContentTypeCompatibleWith(MediaType.TEXT_PLAIN); // ... ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- val spec = client.get().uri("/persons").exchange() val response = RestTestClientResponse.from(spec) assertThat(response).hasStatusOk() assertThat(response).hasContentTypeCompatibleWith(MediaType.TEXT_PLAIN) // ... ---- ====== You can also use the built-in workflow first, and then obtain an `ExchangeResult` to wrap and continue with AssertJ. For example: [tabs] ====== Java:: + [source,java,indent=0,subs="verbatim,quotes"] ---- ExchangeResult result = client.get().uri("/persons").exchange() . // ... .returnResult(); RestTestClientResponse response = RestTestClientResponse.from(result); assertThat(response).hasStatusOk(); assertThat(response).hasContentTypeCompatibleWith(MediaType.TEXT_PLAIN); // ... ---- Kotlin:: + [source,kotlin,indent=0,subs="verbatim,quotes"] ---- val result = client.get().uri("/persons").exchange() . // ... .returnResult() val response = RestTestClientResponse.from(spec) assertThat(response).hasStatusOk() assertThat(response).hasContentTypeCompatibleWith(MediaType.TEXT_PLAIN) // ... ---- ======