Add example of WebClient usage

docs/spring.md

@@ -115,6 +115,18 @@ public Mono<CloudEvent> event(@RequestBody Mono<CloudEvent> body) {
 }
 ```
 
+The `CodecCustomizer` also works on the client side, so you can use it anywhere that you use a `WebClient` (including in an MVC application). Here's a simple example of a Cloud Event HTTP client:
+
+```java
+WebClient client = ...; // Either WebClient.create() or @Autowired a WebClient.Builder
+CloudEvent event = ...; // Create a CloudEvent
+Mono<CloudEvent> response = client.post()
+  .uri("http://localhost:8080/events")
+  .bodyValue(event)
+  .retrieve()
+  .bodyToMono(CloudEvent.class);
+```
+
 ### Messaging
 
 Spring Messaging is applicable in a wide range of use cases including WebSockets, JMS, Apache Kafka, RabbitMQ and others. It is also a core part of the Spring Cloud Function and Spring Cloud Stream libraries, so those are natural tools to use to build applications that use Cloud Events. The core abstraction in Spring is the `Message` which carries headers and a payload, just like a `CloudEvent`. Since the mapping is quite direct it makes sense to have a set of converters for Spring applications, so you can consume and produce `CloudEvents`, by treating them as `Messages`. This project provides a converter that you can register in a Spring Messaging application:

examples/spring-function/src/main/java/io/cloudevents/examples/spring/DemoApplication.java

@@ -4,22 +4,20 @@
 import java.util.UUID;
 import java.util.function.Function;
 
-import io.cloudevents.CloudEvent;
-import io.cloudevents.core.builder.CloudEventBuilder;
-import io.cloudevents.spring.messaging.CloudEventMessageConverter;
-import io.cloudevents.spring.webflux.CloudEventHttpMessageReader;
-import io.cloudevents.spring.webflux.CloudEventHttpMessageWriter;
-
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.boot.web.codec.CodecCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.http.codec.CodecConfigurer;
-import org.springframework.web.bind.annotation.RestController;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.spring.messaging.CloudEventMessageConverter;
+import io.cloudevents.spring.webflux.CloudEventHttpMessageReader;
+import io.cloudevents.spring.webflux.CloudEventHttpMessageWriter;
 
 @SpringBootApplication
-@RestController
 public class DemoApplication {
 
 	public static void main(String[] args) throws Exception {

examples/spring-reactive/src/test/java/io/cloudevents/examples/spring/DemoApplicationTests.java

@@ -3,110 +3,146 @@
 import java.net.URI;
 
 import org.junit.jupiter.api.Test;
-
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
-import org.springframework.boot.test.web.client.TestRestTemplate;
-import org.springframework.boot.web.server.LocalServerPort;
-import org.springframework.http.HttpHeaders;
-import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
-import org.springframework.http.RequestEntity;
-import org.springframework.http.ResponseEntity;
+import org.springframework.test.web.reactive.server.WebTestClient;
 
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
 import static org.assertj.core.api.Assertions.assertThat;
 
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
 public class DemoApplicationTests {
 
-	@Autowired
-	private TestRestTemplate rest;
-
-	@LocalServerPort
-	private int port;
-
-	@Test
-	void echoWithCorrectHeaders() {
-
-		ResponseEntity<String> response = rest
-				.exchange(RequestEntity.post(URI.create("http://localhost:" + port + "/foos")) //
-						.header("ce-id", "12345") //
-						.header("ce-specversion", "1.0") //
-						.header("ce-type", "io.spring.event") //
-						.header("ce-source", "https://spring.io/events") //
-						.contentType(MediaType.APPLICATION_JSON) //
-						.body("{\"value\":\"Dave\"}"), String.class);
-
-		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
-		assertThat(response.getBody()).isEqualTo("{\"value\":\"Dave\"}");
-
-		HttpHeaders headers = response.getHeaders();
-
-		assertThat(headers).containsKey("ce-id");
-		assertThat(headers).containsKey("ce-source");
-		assertThat(headers).containsKey("ce-type");
-
-		assertThat(headers.getFirst("ce-id")).isNotEqualTo("12345");
-		assertThat(headers.getFirst("ce-type")).isEqualTo("io.spring.event.Foo");
-		assertThat(headers.getFirst("ce-source")).isEqualTo("https://spring.io/foos");
-
-	}
-
-	@Test
-	void structuredRequestResponseEvents() {
-
-		ResponseEntity<String> response = rest
-				.exchange(RequestEntity.post(URI.create("http://localhost:" + port + "/event")) //
-						.contentType(new MediaType("application", "cloudevents+json")) //
-						.body("{" //
-								+ "\"id\":\"12345\"," //
-								+ "\"specversion\":\"1.0\"," //
-								+ "\"type\":\"io.spring.event\"," //
-								+ "\"source\":\"https://spring.io/events\"," //
-								+ "\"data\":{\"value\":\"Dave\"}}"),
-						String.class);
-
-		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
-		assertThat(response.getBody()).isEqualTo("{\"value\":\"Dave\"}");
-
-		HttpHeaders headers = response.getHeaders();
-
-		assertThat(headers).containsKey("ce-id");
-		assertThat(headers).containsKey("ce-source");
-		assertThat(headers).containsKey("ce-type");
-
-		assertThat(headers.getFirst("ce-id")).isNotEqualTo("12345");
-		assertThat(headers.getFirst("ce-type")).isEqualTo("io.spring.event.Foo");
-		assertThat(headers.getFirst("ce-source")).isEqualTo("https://spring.io/foos");
-
-	}
-
-	@Test
-	void requestResponseEvents() {
-
-		ResponseEntity<String> response = rest
-				.exchange(RequestEntity.post(URI.create("http://localhost:" + port + "/event")) //
-						.header("ce-id", "12345") //
-						.header("ce-specversion", "1.0") //
-						.header("ce-type", "io.spring.event") //
-						.header("ce-source", "https://spring.io/events") //
-						.contentType(MediaType.APPLICATION_JSON) //
-						.body("{\"value\":\"Dave\"}"), String.class);
-
-		assertThat(response.getStatusCode()).isEqualTo(HttpStatus.OK);
-		assertThat(response.getBody()).isEqualTo("{\"value\":\"Dave\"}");
-
-		HttpHeaders headers = response.getHeaders();
-
-		assertThat(headers).containsKey("ce-id");
-		assertThat(headers).containsKey("ce-source");
-		assertThat(headers).containsKey("ce-type");
-
-		assertThat(headers.getFirst("ce-id")).isNotEqualTo("12345");
-		assertThat(headers.getFirst("ce-type")).isEqualTo("io.spring.event.Foo");
-		assertThat(headers.getFirst("ce-source")).isEqualTo("https://spring.io/foos");
-
-	}
+    @Autowired
+    private WebTestClient rest;
+
+    @Test
+    void echoWithCorrectHeaders() {
+
+        rest.post().uri("/foos").header("ce-id", "12345") //
+                .header("ce-specversion", "1.0") //
+                .header("ce-type", "io.spring.event") //
+                .header("ce-source", "https://spring.io/events") //
+                .contentType(MediaType.APPLICATION_JSON) //
+                .bodyValue("{\"value\":\"Dave\"}") //
+                .exchange() //
+                .expectStatus().isOk() //
+                .expectHeader().exists("ce-id") //
+                .expectHeader().exists("ce-source") //
+                .expectHeader().exists("ce-type") //
+                .expectHeader().value("ce-id", value -> {
+                    if (value.equals("12345"))
+                        throw new IllegalStateException();
+                }) //
+                .expectHeader().valueEquals("ce-type", "io.spring.event.Foo") //
+                .expectHeader().valueEquals("ce-source", "https://spring.io/foos") //
+                .expectBody(String.class).isEqualTo("{\"value\":\"Dave\"}");
+
+    }
+
+    @Test
+    void structuredRequestResponseEvents() {
+
+        rest.post().uri("/event") //
+                .contentType(new MediaType("application", "cloudevents+json")) //
+                .bodyValue("{" //
+                        + "\"id\":\"12345\"," //
+                        + "\"specversion\":\"1.0\"," //
+                        + "\"type\":\"io.spring.event\"," //
+                        + "\"source\":\"https://spring.io/events\"," //
+                        + "\"data\":{\"value\":\"Dave\"}}") //
+                .exchange() //
+                .expectStatus().isOk() //
+                .expectHeader().exists("ce-id") //
+                .expectHeader().exists("ce-source") //
+                .expectHeader().exists("ce-type") //
+                .expectHeader().value("ce-id", value -> {
+                    if (value.equals("12345"))
+                        throw new IllegalStateException();
+                }) //
+                .expectHeader().valueEquals("ce-type", "io.spring.event.Foo") //
+                .expectHeader().valueEquals("ce-source", "https://spring.io/foos") //
+                .expectBody(String.class).isEqualTo("{\"value\":\"Dave\"}");
+
+    }
+
+    @Test
+    void structuredRequestResponseCloudEventToString() {
+
+        rest.post().uri("/event") //
+                .bodyValue(CloudEventBuilder.v1() //
+                        .withId("12345") //
+                        .withType("io.spring.event") //
+                        .withSource(URI.create("https://spring.io/events")).withData("{\"value\":\"Dave\"}".getBytes()) //
+                        .build()) //
+                .exchange() //
+                .expectStatus().isOk() //
+                .expectHeader().exists("ce-id") //
+                .expectHeader().exists("ce-source") //
+                .expectHeader().exists("ce-type") //
+                .expectHeader().value("ce-id", value -> {
+                    if (value.equals("12345"))
+                        throw new IllegalStateException();
+                }) //
+                .expectHeader().valueEquals("ce-type", "io.spring.event.Foo") //
+                .expectHeader().valueEquals("ce-source", "https://spring.io/foos") //
+                .expectBody(String.class).isEqualTo("{\"value\":\"Dave\"}");
+
+    }
+
+    @Test
+    void structuredRequestResponseCloudEventToCloudEvent() {
+
+        rest.post().uri("/event") //
+                .accept(new MediaType("application", "cloudevents+json")) //
+                .bodyValue(CloudEventBuilder.v1() //
+                        .withId("12345") //
+                        .withType("io.spring.event") //
+                        .withSource(URI.create("https://spring.io/events")) //
+                        .withData("{\"value\":\"Dave\"}".getBytes()) //
+                        .build()) //
+                .exchange() //
+                .expectStatus().isOk() //
+                .expectHeader().exists("ce-id") //
+                .expectHeader().exists("ce-source") //
+                .expectHeader().exists("ce-type") //
+                .expectHeader().value("ce-id", value -> {
+                    if (value.equals("12345"))
+                        throw new IllegalStateException();
+                }) //
+                .expectHeader().valueEquals("ce-type", "io.spring.event.Foo") //
+                .expectHeader().valueEquals("ce-source", "https://spring.io/foos") //
+                .expectBody(CloudEvent.class) //
+                .value(event -> assertThat(new String(event.getData().toBytes())) //
+                        .isEqualTo("{\"value\":\"Dave\"}"));
+
+    }
+
+    @Test
+    void requestResponseEvents() {
+
+        rest.post().uri("/event").header("ce-id", "12345") //
+                .header("ce-specversion", "1.0") //
+                .header("ce-type", "io.spring.event") //
+                .header("ce-source", "https://spring.io/events") //
+                .contentType(MediaType.APPLICATION_JSON) //
+                .bodyValue("{\"value\":\"Dave\"}") //
+                .exchange() //
+                .expectStatus().isOk() //
+                .expectHeader().exists("ce-id") //
+                .expectHeader().exists("ce-source") //
+                .expectHeader().exists("ce-type") //
+                .expectHeader().value("ce-id", value -> {
+                    if (value.equals("12345"))
+                        throw new IllegalStateException();
+                }) //
+                .expectHeader().valueEquals("ce-type", "io.spring.event.Foo") //
+                .expectHeader().valueEquals("ce-source", "https://spring.io/foos") //
+                .expectBody(String.class).isEqualTo("{\"value\":\"Dave\"}");
+
+    }
 
 }

examples/spring-reactive/src/test/java/io/cloudevents/examples/spring/WebClientTests.java

@@ -0,0 +1,58 @@
+package io.cloudevents.examples.spring;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.net.URI;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.boot.web.server.LocalServerPort;
+import org.springframework.web.reactive.function.client.WebClient;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import reactor.core.publisher.Mono;
+
+/**
+ * Test case to show example usage of WebClient and CloudEvent. The actual
+ * content of the request and response are asserted separately in
+ * {@link DemoApplicationTests}.
+ */
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+public class WebClientTests {
+
+    @Autowired
+    private WebClient.Builder rest;
+
+    @LocalServerPort
+    private int port;
+
+    private CloudEvent event;
+
+    @BeforeEach
+    void setUp() {
+        event = CloudEventBuilder.v1() //
+                .withId("12345") //
+                .withSource(URI.create("https://spring.io/events")) //
+                .withType("io.spring.event") //
+                .withData("{\"value\":\"Dave\"}".getBytes()) //
+                .build();
+    }
+
+    @Test
+    void echoWithCorrectHeaders() {
+
+        Mono<CloudEvent> result = rest.build() //
+                .post() //
+                .uri("http://localhost:" + port + "/event") //
+                .bodyValue(event) //
+                .exchangeToMono(response -> response.bodyToMono(CloudEvent.class));
+
+        assertThat(result.block().getData()).isEqualTo(event.getData());
+
+    }
+
+}