Add initial RequestHeaderArgumentResolver implementation and tests.

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

@@ -135,6 +135,12 @@ class PathVariableArgumentResolverTests {
 				.isThrownBy(() -> this.service.executeOptionalValueMap(Map.of("id", Optional.empty())));
 	}
 
+	@Test
+	void shouldResolvePathVariableNameFromObjectMapKey() {
+		this.service.executeValueMapWithObjectKey(Map.of(Boolean.TRUE, "true"));
+		assertPathVariable("true", "true");
+	}
+
 	@SuppressWarnings("SameParameterValue")
 	private void assertPathVariable(String name, @Nullable String expectedValue) {
 		assertThat(getActualUriVariables().get(name)).isEqualTo(expectedValue);
@@ -178,6 +184,9 @@ class PathVariableArgumentResolverTests {
 		@GetExchange
 		void executeValueMap(@Nullable @PathVariable Map<String, String> map);
 
+		@GetExchange
+		void executeValueMapWithObjectKey(@Nullable @PathVariable Map<Object, String> map);
+
 		@GetExchange
 		void executeOptionalValueMap(@PathVariable Map<String, Optional<String>> map);
 	}

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

@@ -0,0 +1,198 @@
+/*
+ * 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 java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+import org.apache.groovy.util.Maps;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
+import org.springframework.web.bind.annotation.RequestHeader;
+import org.springframework.web.service.annotation.GetExchange;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+
+/**
+ * Tests for {@link RequestHeaderArgumentResolver}.
+ *
+ * @author Olga Maciaszek-Sharma
+ */
+class RequestHeaderArgumentResolverTests {
+
+	private final TestHttpClientAdapter clientAdapter = new TestHttpClientAdapter();
+
+	private final Service service = this.clientAdapter.createService(Service.class);
+
+	@Test
+	void shouldResolveSingleValueRequestHeader() {
+		this.service.executeString("test");
+		assertRequestHeaders("id", "test");
+	}
+
+	@Test
+	void shouldResolveRequestHeaderWithNameFromAnnotationName() {
+		this.service.executeNamed("test");
+		assertRequestHeaders("id", "test");
+	}
+
+	@Test
+	void shouldResolveRequestHeaderNameFromValue() {
+		this.service.executeNamedWithValue("test");
+		assertRequestHeaders("test", "test");
+	}
+
+	@Test
+	void shouldResolveObjectValueRequestHeader() {
+		this.service.execute(Boolean.TRUE);
+		assertRequestHeaders("id", "true");
+	}
+
+	@Test
+	void shouldResolveListRequestHeader() {
+		this.service.execute(List.of("test1", Boolean.TRUE, "test3"));
+		assertRequestHeaders("id", "test1", "true", "test3");
+	}
+
+	@Test
+	void shouldResolveArrayRequestHeader() {
+		this.service.execute("test1", Boolean.FALSE, "test3");
+		assertRequestHeaders("id", "test1", "false", "test3");
+	}
+
+	@Test
+	void shouldResolveRequestHeadersFromMap() {
+		this.service.executeMap(Maps.of(Boolean.TRUE, "true", Boolean.FALSE, "false"));
+		assertRequestHeaders("true", "true");
+		assertRequestHeaders("false", "false");
+	}
+
+	@Test
+	void shouldThrowExceptionWhenRequiredHeaderNull() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> this.service.executeString(null));
+	}
+
+	@Test
+	void shouldIgnoreNullWhenHeaderNotRequired() {
+		this.service.executeNotRequired(null);
+		assertThat(getActualHeaders().get("id")).isNull();
+	}
+
+	@Test
+	void shouldIgnoreNullMapValue() {
+		this.service.executeMap(null);
+		assertThat(getActualHeaders()).isEmpty();
+	}
+
+	@Test
+	void shouldResolveRequestHeaderFromOptionalArgumentWithConversion() {
+		this.service.executeOptional(Optional.of(Boolean.TRUE));
+		assertRequestHeaders("id", "true");
+	}
+
+	@Test
+	void shouldResolveRequestHeaderFromOptionalArgument() {
+		this.service.executeOptional(Optional.of("test"));
+		assertRequestHeaders("id", "test");
+	}
+
+	@Test
+	void shouldThrowExceptionForEmptyOptional() {
+		assertThatIllegalArgumentException().isThrownBy(() -> this.service.execute(Optional.empty()));
+	}
+
+	@Test
+	void shouldIgnoreEmptyOptionalWhenNotRequired() {
+		this.service.executeOptionalNotRequired(Optional.empty());
+		assertThat(getActualHeaders().get("id")).isNull();
+	}
+
+	@Test
+	void shouldResolveRequestHeaderFromOptionalMapValue() {
+		this.service.executeOptionalMapValue(Map.of("id", Optional.of("test")));
+		assertRequestHeaders("id", "test");
+	}
+
+	@Test
+	void shouldReplaceNullValueWithDefaultWhenAvailable() {
+		this.service.executeWithDefaultValue(null);
+		assertRequestHeaders("id", "default");
+	}
+
+	@Test
+	void shouldReplaceEmptyOptionalValueWithDefaultWhenAvailable() {
+		this.service.executeOptionalWithDefaultValue(Optional.empty());
+		assertRequestHeaders("id", "default");
+	}
+
+	private void assertRequestHeaders(String key, String... values) {
+		assertThat(getActualHeaders().get(key)).containsOnly(values);
+	}
+
+	private HttpHeaders getActualHeaders() {
+		return this.clientAdapter.getRequestValues().getHeaders();
+	}
+
+	@SuppressWarnings("OptionalUsedAsFieldOrParameterType")
+	private interface Service {
+
+		@GetExchange
+		void executeString(@Nullable @RequestHeader String id);
+
+		@GetExchange
+		void executeNotRequired(@Nullable @RequestHeader(required = false) String id);
+
+		@GetExchange
+		void execute(@RequestHeader Object id);
+
+		@GetExchange
+		void execute(@RequestHeader List<Object> id);
+
+		@GetExchange
+		void execute(@RequestHeader Object... id);
+
+		@GetExchange
+		void executeMap(@Nullable @RequestHeader Map<Object, String> id);
+
+		@GetExchange
+		void executeOptionalMapValue(@RequestHeader Map<Object, Optional<String>> id);
+
+		@GetExchange
+		void executeOptional(@RequestHeader Optional<Object> id);
+
+		@GetExchange
+		void executeOptionalNotRequired(@RequestHeader(required = false) Optional<String> id);
+
+		@GetExchange
+		void executeNamedWithValue(@Nullable @RequestHeader(name = "id", value = "test") String employeeId);
+
+		@GetExchange
+		void executeNamed(@RequestHeader(name = "id") String employeeId);
+
+		@GetExchange
+		void executeWithDefaultValue(@Nullable @RequestHeader(defaultValue = "default") String id);
+
+		@GetExchange
+		void executeOptionalWithDefaultValue(@Nullable @RequestHeader(defaultValue = "default") Optional<Object> id);
+	}
+
+}