Support for mutating ServerWebExchange in WebTestClient

This commit adds a common base class for server-less setup with the
option to configure a transformation function on the
ServerWebExchange for every request.

The transformation is applied through a WebFilter. As a result the
RouterFunction setup is now invoked behind a DispatcherHandler with
a HandlerMapping + HandlerAdapter.

Issue: SPR-15250

spring-test/src/test/java/org/springframework/test/web/reactive/server/DefaultControllerSpecTests.java

@@ -17,10 +17,11 @@ package org.springframework.test.web.reactive.server;
 
 import org.junit.Test;
 
-import org.springframework.context.ApplicationContext;
-import org.springframework.context.annotation.AnnotationConfigApplicationContext;
-
-import static org.junit.Assert.assertSame;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
 
 /**
  * Unit tests for {@link DefaultControllerSpec}.
@@ -29,44 +30,47 @@ import static org.junit.Assert.assertSame;
 public class DefaultControllerSpecTests {
 
 	@Test
-	public void controllers() throws Exception {
-		OneController controller1 = new OneController();
-		SecondController controller2 = new SecondController();
-
-		TestControllerSpec spec = new TestControllerSpec(controller1, controller2);
-		ApplicationContext context = spec.createApplicationContext();
-
-		assertSame(controller1, context.getBean(OneController.class));
-		assertSame(controller2, context.getBean(SecondController.class));
+	public void controller() throws Exception {
+		new DefaultControllerSpec(new MyController()).build()
+				.get().uri("/")
+				.exchange()
+				.expectStatus().isOk()
+				.expectBody(String.class).value().isEqualTo("Success");
 	}
 
 	@Test
 	public void controllerAdvice() throws Exception {
-		OneControllerAdvice advice = new OneControllerAdvice();
-
-		TestControllerSpec spec = new TestControllerSpec(new OneController());
-		spec.controllerAdvice(advice);
-		ApplicationContext context = spec.createApplicationContext();
-
-		assertSame(advice, context.getBean(OneControllerAdvice.class));
+		new DefaultControllerSpec(new MyController())
+				.controllerAdvice(new MyControllerAdvice())
+				.build()
+				.get().uri("/exception")
+				.exchange()
+				.expectStatus().isBadRequest()
+				.expectBody(String.class).value().isEqualTo("Handled exception");
 	}
 
-	private static class OneController {}
 
-	private static class SecondController {}
+	@RestController
+	private static class MyController {
 
-	private static class OneControllerAdvice {}
-
-
-	private static class TestControllerSpec extends DefaultControllerSpec {
-
-		TestControllerSpec(Object... controllers) {
-			super(controllers);
+		@GetMapping("/")
+		public String handle() {
+			return "Success";
 		}
 
-		@Override
-		public AnnotationConfigApplicationContext createApplicationContext() {
-			return super.createApplicationContext();
+		@GetMapping("/exception")
+		public void handleWithError() {
+			throw new IllegalStateException();
+		}
+
+	}
+
+	@ControllerAdvice
+	private static class MyControllerAdvice {
+
+		@ExceptionHandler
+		public ResponseEntity<String> handle(IllegalStateException ex) {
+			return ResponseEntity.status(400).body("Handled exception");
 		}
 	}
 

spring-test/src/test/java/org/springframework/test/web/reactive/server/samples/bind/ApplicationContextTests.java

@@ -15,8 +15,12 @@
  */
 package org.springframework.test.web.reactive.server.samples.bind;
 
+import java.security.Principal;
+import java.util.function.Function;
+
 import org.junit.Before;
 import org.junit.Test;
+import reactor.core.publisher.Mono;
 
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -25,6 +29,10 @@ import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.reactive.config.EnableWebFlux;
+import org.springframework.web.server.ServerWebExchange;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 /**
  * Binding to server infrastructure declared in a Spring ApplicationContext.
@@ -44,15 +52,26 @@ public class ApplicationContextTests {
 		context.register(WebConfig.class);
 		context.refresh();
 
-		this.client = WebTestClient.bindToApplicationContext(context).build();
+		this.client = WebTestClient.bindToApplicationContext(context)
+				.exchangeMutator(identityMutator("Pablo"))
+				.build();
 	}
 
+	private Function<ServerWebExchange, ServerWebExchange> identityMutator(String userName) {
+		return exchange -> {
+			Principal user = mock(Principal.class);
+			when(user.getName()).thenReturn(userName);
+			return exchange.mutate().principal(Mono.just(user)).build();
+		};
+	}
+
+
 	@Test
 	public void test() throws Exception {
 		this.client.get().uri("/test")
 				.exchange()
 				.expectStatus().isOk()
-				.expectBody(String.class).value().isEqualTo("It works!");
+				.expectBody(String.class).value().isEqualTo("Hello Pablo!");
 	}
 
 
@@ -71,8 +90,8 @@ public class ApplicationContextTests {
 	static class TestController {
 
 		@GetMapping("/test")
-		public String handle() {
-			return "It works!";
+		public String handle(Principal principal) {
+			return "Hello " + principal.getName() + "!";
 		}
 	}
 

spring-test/src/test/java/org/springframework/test/web/reactive/server/samples/bind/ControllerTests.java

@@ -15,12 +15,20 @@
  */
 package org.springframework.test.web.reactive.server.samples.bind;
 
+import java.security.Principal;
+import java.util.function.Function;
+
 import org.junit.Before;
 import org.junit.Test;
+import reactor.core.publisher.Mono;
 
 import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.server.ServerWebExchange;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 /**
  * Bind to annotated controllers.
@@ -35,7 +43,18 @@ public class ControllerTests {
 
 	@Before
 	public void setUp() throws Exception {
-		this.client = WebTestClient.bindToController(new TestController()).build();
+
+		this.client = WebTestClient.bindToController(new TestController())
+				.exchangeMutator(identityMutator("Pablo"))
+				.build();
+	}
+
+	private Function<ServerWebExchange, ServerWebExchange> identityMutator(String userName) {
+		return exchange -> {
+			Principal user = mock(Principal.class);
+			when(user.getName()).thenReturn(userName);
+			return exchange.mutate().principal(Mono.just(user)).build();
+		};
 	}
 
 
@@ -44,7 +63,7 @@ public class ControllerTests {
 		this.client.get().uri("/test")
 				.exchange()
 				.expectStatus().isOk()
-				.expectBody(String.class).value().isEqualTo("It works!");
+				.expectBody(String.class).value().isEqualTo("Hello Pablo!");
 	}
 
 
@@ -52,8 +71,9 @@ public class ControllerTests {
 	static class TestController {
 
 		@GetMapping("/test")
-		public String handle() {
-			return "It works!";
+		public String handle(Principal principal) {
+			return "Hello " + principal.getName() + "!";
 		}
 	}
+
 }