Support HTTP Interface clients in test framework

framework-docs/modules/ROOT/pages/integration/rest-clients.adoc

@@ -1029,6 +1029,26 @@ to a client application, what input and output types to create, what endpoint me
 signatures are needed, what Javadoc to have, and so on. The resulting Java API guides and
 is ready to use.
 
+For testing, an HTTP Interface Client can also be backed by `WebTestClient` or
+`RestTestClient` so that an `@HttpExchange` interface can be invoked against a mock
+server (for example a controller bound via `WebTestClient.bindToController(...)` or
+`RestTestClient.bindToController(...)`):
+
+[source,java,indent=0,subs="verbatim,quotes"]
+----
+	// Using RestTestClient...
+
+	RestTestClient client = RestTestClient.bindToController(new MyController()).build();
+	RestTestClientAdapter adapter = RestTestClientAdapter.create(client);
+
+	// or WebTestClient...
+
+	WebTestClient client = WebTestClient.bindToController(new MyController()).build();
+	WebTestClientAdapter adapter = WebTestClientAdapter.create(client);
+
+	HttpServiceProxyFactory factory = HttpServiceProxyFactory.builderFor(adapter).build();
+----
+
 
 [[rest-http-service-client-method-parameters]]
 === Method Parameters

spring-test/src/main/java/org/springframework/test/web/reactive/server/support/WebTestClientAdapter.java

@@ -0,0 +1,142 @@
+/*
+ * Copyright 2002-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.test.web.reactive.server.support;
+
+import java.net.URI;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.ResponseEntity;
+import org.springframework.test.web.reactive.server.EntityExchangeResult;
+import org.springframework.test.web.reactive.server.ExchangeResult;
+import org.springframework.test.web.reactive.server.WebTestClient;
+import org.springframework.util.Assert;
+import org.springframework.web.service.invoker.HttpExchangeAdapter;
+import org.springframework.web.service.invoker.HttpRequestValues;
+import org.springframework.web.service.invoker.HttpServiceProxyFactory;
+import org.springframework.web.util.UriBuilderFactory;
+
+/**
+ * {@link HttpExchangeAdapter} that enables an {@link HttpServiceProxyFactory}
+ * to use {@link WebTestClient} for request execution.
+ *
+ * <p>Use static factory methods in this class to create an
+ * {@link HttpServiceProxyFactory} configured with the given {@link WebTestClient}.
+ *
+ * @author Devendra Reddy Pennabadi
+ * @since 7.0
+ */
+public final class WebTestClientAdapter implements HttpExchangeAdapter {
+
+	private final WebTestClient webTestClient;
+
+
+	private WebTestClientAdapter(WebTestClient webTestClient) {
+		this.webTestClient = webTestClient;
+	}
+
+
+	@Override
+	public boolean supportsRequestAttributes() {
+		return true;
+	}
+
+	@Override
+	public void exchange(HttpRequestValues values) {
+		newRequest(values).exchange().returnResult(Void.class);
+	}
+
+	@Override
+	public HttpHeaders exchangeForHeaders(HttpRequestValues values) {
+		return newRequest(values).exchange().returnResult(Void.class).getResponseHeaders();
+	}
+
+	@Override
+	public <T> @Nullable T exchangeForBody(HttpRequestValues values, ParameterizedTypeReference<T> bodyType) {
+		return newRequest(values).exchange().expectBody(bodyType).returnResult().getResponseBody();
+	}
+
+	@Override
+	public ResponseEntity<Void> exchangeForBodilessEntity(HttpRequestValues values) {
+		ExchangeResult result = newRequest(values).exchange().returnResult(Void.class);
+		return ResponseEntity.status(result.getStatus())
+				.headers(result.getResponseHeaders())
+				.build();
+	}
+
+	@Override
+	public <T> ResponseEntity<T> exchangeForEntity(HttpRequestValues values, ParameterizedTypeReference<T> bodyType) {
+		EntityExchangeResult<T> result = newRequest(values).exchange().expectBody(bodyType).returnResult();
+		return ResponseEntity.status(result.getStatus())
+				.headers(result.getResponseHeaders())
+				.body(result.getResponseBody());
+	}
+
+	private WebTestClient.RequestBodySpec newRequest(HttpRequestValues values) {
+		HttpMethod method = values.getHttpMethod();
+		Assert.notNull(method, "HttpMethod is required");
+
+		WebTestClient.RequestBodyUriSpec uriSpec = this.webTestClient.method(method);
+		WebTestClient.RequestBodySpec spec = setUri(uriSpec, values);
+
+		spec.headers(headers -> headers.putAll(values.getHeaders()));
+		spec.cookies(cookies -> cookies.putAll(values.getCookies()));
+		if (values.getApiVersion() != null) {
+			spec.apiVersion(values.getApiVersion());
+		}
+		spec.attributes(attributes -> attributes.putAll(values.getAttributes()));
+		setBody(spec, values);
+		return spec;
+	}
+
+	private static WebTestClient.RequestBodySpec setUri(
+			WebTestClient.RequestBodyUriSpec spec, HttpRequestValues values) {
+
+		if (values.getUri() != null) {
+			return spec.uri(values.getUri());
+		}
+		if (values.getUriTemplate() != null) {
+			UriBuilderFactory uriBuilderFactory = values.getUriBuilderFactory();
+			if (uriBuilderFactory != null) {
+				URI uri = uriBuilderFactory.expand(values.getUriTemplate(), values.getUriVariables());
+				return spec.uri(uri);
+			}
+			return spec.uri(values.getUriTemplate(), values.getUriVariables());
+		}
+		throw new IllegalStateException("Neither full URL nor URI template");
+	}
+
+	private static void setBody(WebTestClient.RequestBodySpec spec, HttpRequestValues values) {
+		if (values.getBodyValue() != null) {
+			spec.bodyValue(values.getBodyValue());
+		}
+	}
+
+
+	/**
+	 * Create a {@link WebTestClientAdapter} for the given {@link WebTestClient}.
+	 * @param webTestClient the test client to use
+	 * @return the created adapter instance
+	 */
+	public static WebTestClientAdapter create(WebTestClient webTestClient) {
+		return new WebTestClientAdapter(webTestClient);
+	}
+
+}

spring-test/src/main/java/org/springframework/test/web/reactive/server/support/package-info.java

@@ -0,0 +1,8 @@
+/**
+ * Classes supporting the {@code org.springframework.test.web.reactive.server} package.
+ * Contains an {@code HttpExchangeAdapter} backed by {@code WebTestClient}.
+ */
+@NullMarked
+package org.springframework.test.web.reactive.server.support;
+
+import org.jspecify.annotations.NullMarked;

spring-test/src/main/java/org/springframework/test/web/servlet/client/support/RestTestClientAdapter.java

@@ -0,0 +1,152 @@
+/*
+ * Copyright 2002-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.test.web.servlet.client.support;
+
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.HttpCookie;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.ResponseEntity;
+import org.springframework.test.web.servlet.client.EntityExchangeResult;
+import org.springframework.test.web.servlet.client.ExchangeResult;
+import org.springframework.test.web.servlet.client.RestTestClient;
+import org.springframework.util.Assert;
+import org.springframework.web.service.invoker.HttpExchangeAdapter;
+import org.springframework.web.service.invoker.HttpRequestValues;
+import org.springframework.web.service.invoker.HttpServiceProxyFactory;
+import org.springframework.web.util.UriBuilderFactory;
+
+/**
+ * {@link HttpExchangeAdapter} that enables an {@link HttpServiceProxyFactory}
+ * to use {@link RestTestClient} for request execution.
+ *
+ * <p>Use static factory methods in this class to create an
+ * {@link HttpServiceProxyFactory} configured with the given {@link RestTestClient}.
+ *
+ * @author Devendra Reddy Pennabadi
+ * @since 7.0
+ */
+public final class RestTestClientAdapter implements HttpExchangeAdapter {
+
+	private final RestTestClient restTestClient;
+
+
+	private RestTestClientAdapter(RestTestClient restTestClient) {
+		this.restTestClient = restTestClient;
+	}
+
+
+	@Override
+	public boolean supportsRequestAttributes() {
+		return true;
+	}
+
+	@Override
+	public void exchange(HttpRequestValues values) {
+		newRequest(values).exchange().returnResult();
+	}
+
+	@Override
+	public HttpHeaders exchangeForHeaders(HttpRequestValues values) {
+		return newRequest(values).exchange().returnResult().getResponseHeaders();
+	}
+
+	@Override
+	public <T> @Nullable T exchangeForBody(HttpRequestValues values, ParameterizedTypeReference<T> bodyType) {
+		return newRequest(values).exchange().expectBody(bodyType).returnResult().getResponseBody();
+	}
+
+	@Override
+	public ResponseEntity<Void> exchangeForBodilessEntity(HttpRequestValues values) {
+		ExchangeResult result = newRequest(values).exchange().returnResult();
+		return ResponseEntity.status(result.getStatus())
+				.headers(result.getResponseHeaders())
+				.build();
+	}
+
+	@Override
+	public <T> ResponseEntity<T> exchangeForEntity(HttpRequestValues values, ParameterizedTypeReference<T> bodyType) {
+		EntityExchangeResult<T> result = newRequest(values).exchange().expectBody(bodyType).returnResult();
+		return ResponseEntity.status(result.getStatus())
+				.headers(result.getResponseHeaders())
+				.body(result.getResponseBody());
+	}
+
+	private RestTestClient.RequestBodySpec newRequest(HttpRequestValues values) {
+		HttpMethod method = values.getHttpMethod();
+		Assert.notNull(method, "HttpMethod is required");
+
+		RestTestClient.RequestBodyUriSpec uriSpec = this.restTestClient.method(method);
+		RestTestClient.RequestBodySpec spec = setUri(uriSpec, values);
+
+		spec.headers(headers -> headers.putAll(values.getHeaders()));
+		setCookieHeader(spec, values);
+		if (values.getApiVersion() != null) {
+			spec.apiVersion(values.getApiVersion());
+		}
+		spec.attributes(attributes -> attributes.putAll(values.getAttributes()));
+		if (values.getBodyValue() != null) {
+			spec.body(values.getBodyValue());
+		}
+		return spec;
+	}
+
+	private static RestTestClient.RequestBodySpec setUri(
+			RestTestClient.RequestBodyUriSpec spec, HttpRequestValues values) {
+
+		if (values.getUri() != null) {
+			return spec.uri(values.getUri());
+		}
+		if (values.getUriTemplate() != null) {
+			UriBuilderFactory uriBuilderFactory = values.getUriBuilderFactory();
+			if (uriBuilderFactory != null) {
+				URI uri = uriBuilderFactory.expand(values.getUriTemplate(), values.getUriVariables());
+				return spec.uri(uri);
+			}
+			return spec.uri(values.getUriTemplate(), values.getUriVariables());
+		}
+		throw new IllegalStateException("Neither full URL nor URI template");
+	}
+
+	private static void setCookieHeader(RestTestClient.RequestBodySpec spec, HttpRequestValues values) {
+		if (!values.getCookies().isEmpty()) {
+			List<String> cookies = new ArrayList<>();
+			values.getCookies().forEach((name, cookieValues) -> cookieValues.forEach(value -> {
+				HttpCookie cookie = new HttpCookie(name, value);
+				cookies.add(cookie.toString());
+			}));
+			spec.header(HttpHeaders.COOKIE, String.join("; ", cookies));
+		}
+	}
+
+
+	/**
+	 * Create a {@link RestTestClientAdapter} for the given {@link RestTestClient}.
+	 * @param restTestClient the test client to use
+	 * @return the created adapter instance
+	 */
+	public static RestTestClientAdapter create(RestTestClient restTestClient) {
+		return new RestTestClientAdapter(restTestClient);
+	}
+
+}

spring-test/src/main/java/org/springframework/test/web/servlet/client/support/package-info.java

@@ -0,0 +1,8 @@
+/**
+ * Classes supporting the {@code org.springframework.test.web.servlet.client} package.
+ * Contains an {@code HttpExchangeAdapter} backed by {@code RestTestClient}.
+ */
+@NullMarked
+package org.springframework.test.web.servlet.client.support;
+
+import org.jspecify.annotations.NullMarked;