Support @RequestPart for @HttpExchange methods

Closes gh-29420

spring-web/src/test/java/org/springframework/web/service/invoker/RequestPartArgumentResolverTests.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2002-2022 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.web.service.invoker;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Mono;
+
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.bind.annotation.RequestPart;
+import org.springframework.web.service.annotation.PostExchange;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for {@link RequestPartArgumentResolver}.
+ *
+ * <p>Additional tests for this resolver:
+ * <ul>
+ * <li>Base class functionality in {@link NamedValueArgumentResolverTests}
+ * <li>Form data vs query params in {@link HttpRequestValuesTests}
+ * </ul>
+ *
+ * @author Rossen Stoyanchev
+ */
+public class RequestPartArgumentResolverTests {
+
+	private final TestHttpClientAdapter client = new TestHttpClientAdapter();
+
+	private Service service;
+
+
+	@BeforeEach
+	void setUp() throws Exception {
+		HttpServiceProxyFactory proxyFactory = HttpServiceProxyFactory.builder(this.client).build();
+		this.service = proxyFactory.createClient(Service.class);
+	}
+
+
+	// Base class functionality should be tested in NamedValueArgumentResolverTests.
+	// Form data vs query params tested in HttpRequestValuesTests.
+
+	@Test
+	void requestPart() {
+		HttpHeaders headers = new HttpHeaders();
+		headers.add("foo", "bar");
+		HttpEntity<String> part2 = new HttpEntity<>("part 2", headers);
+		this.service.postMultipart("part 1", part2, Mono.just("part 3"));
+
+		Object body = this.client.getRequestValues().getBodyValue();
+		assertThat(body).isNotNull().isInstanceOf(MultiValueMap.class);
+		MultiValueMap<String, HttpEntity<?>> map = (MultiValueMap<String, HttpEntity<?>>) body;
+
+		assertThat(map.getFirst("part1").getBody()).isEqualTo("part 1");
+		assertThat(map.getFirst("part2")).isEqualTo(part2);
+		assertThat(((Mono<?>) map.getFirst("part3").getBody()).block()).isEqualTo("part 3");
+	}
+
+
+	private interface Service {
+
+		@PostExchange
+		void postMultipart(@RequestPart String part1, @RequestPart HttpEntity<String> part2, @RequestPart Mono<String> part3);
+
+	}
+
+}