Add Cookie attributes + SameSite CookieResultMatchers in MockMvc

This commit adds assertions to MockMvc's CookieresultMatchers:
 - `attribute` for arbitrary attributes
 - `sameSite` for the SameSite well-known attribute

Note that the `sameSite` methods delegate to their `attribute`
counterparts. Note also that Jakarta's `Cookie#getAttribute` method is
case-insensitive, which is reflected in the documentation of the
`attribute` assertion method and the tests.

Closes gh-30285

spring-test/src/main/java/org/springframework/test/web/servlet/result/CookieResultMatchers.java

@@ -146,6 +146,24 @@ public class CookieResultMatchers {
 		};
 	}
 
+	/**
+	 * Assert a cookie's SameSite attribute with a Hamcrest {@link Matcher}.
+	 * @since 6.0.8
+	 * @see #attribute(String, String, Matcher)
+	 */
+	public ResultMatcher sameSite(String name, Matcher<? super String> matcher) {
+		return attribute(name, "SameSite", matcher);
+	}
+
+	/**
+	 * Assert a cookie's SameSite attribute.
+	 * @since 6.0.8
+	 * @see #attribute(String, String, String)
+	 */
+	public ResultMatcher sameSite(String name, String sameSite) {
+		return attribute(name, "SameSite", sameSite);
+	}
+
 	/**
 	 * Assert a cookie's comment with a Hamcrest {@link Matcher}.
 	 */
@@ -211,6 +229,34 @@ public class CookieResultMatchers {
 		};
 	}
 
+	/**
+	 * Assert a cookie's specified attribute with a Hamcrest {@link Matcher}.
+	 * @param cookieAttribute the name of the Cookie attribute (case-insensitive)
+	 * @since 6.0.8
+	 */
+	public ResultMatcher attribute(String cookieName, String cookieAttribute, Matcher<? super String> matcher) {
+		return result -> {
+			Cookie cookie = getCookie(result, cookieName);
+			String attribute = cookie.getAttribute(cookieAttribute);
+			assertNotNull("Response cookie '" + cookieName + "' doesn't have attribute '" + cookieAttribute + "'", attribute);
+			assertThat("Response cookie '" + cookieName + "' attribute '" + cookieAttribute + "'",
+					attribute, matcher);
+		};
+	}
+
+	/**
+	 * Assert a cookie's specified attribute.
+	 * @param cookieAttribute the name of the Cookie attribute (case-insensitive)
+	 * @since 6.0.8
+	 */
+	public ResultMatcher attribute(String cookieName, String cookieAttribute, String attributeValue) {
+		return result -> {
+			Cookie cookie = getCookie(result, cookieName);
+			assertEquals("Response cookie '" + cookieName + "' attribute '" + cookieAttribute + "'",
+					attributeValue, cookie.getAttribute(cookieAttribute));
+		};
+	}
+
 
 	private static Cookie getCookie(MvcResult result, String name) {
 		Cookie cookie = result.getResponse().getCookie(name);

spring-test/src/main/kotlin/org/springframework/test/web/servlet/result/CookieResultMatchersDsl.kt

@@ -99,6 +99,20 @@ class CookieResultMatchersDsl internal constructor (private val actions: ResultA
 		actions.andExpect(matchers.domain(name, domain))
 	}
 
+	/**
+	 * @see CookieResultMatchers.sameSite
+	 */
+	fun sameSite(name: String, matcher: Matcher<String>) {
+		actions.andExpect(matchers.sameSite(name, matcher))
+	}
+
+	/**
+	 * @see CookieResultMatchers.sameSite
+	 */
+	fun sameSite(name: String, sameSite: String) {
+		actions.andExpect(matchers.sameSite(name, sameSite))
+	}
+
 	/**
 	 * @see CookieResultMatchers.comment
 	 */
@@ -140,4 +154,18 @@ class CookieResultMatchersDsl internal constructor (private val actions: ResultA
 	fun httpOnly(name: String, httpOnly: Boolean) {
 		actions.andExpect(matchers.httpOnly(name, httpOnly))
 	}
+
+	/**
+	 * @see CookieResultMatchers.attribute
+	 */
+	fun attribute(name: String, attributeName: String, matcher: Matcher<String>) {
+		actions.andExpect(matchers.attribute(name, attributeName, matcher))
+	}
+
+	/**
+	 * @see CookieResultMatchers.attribute
+	 */
+	fun attribute(name: String, attributeName: String, attributeValue: String) {
+		actions.andExpect(matchers.attribute(name, attributeName, attributeValue))
+	}
 }

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/resultmatchers/CookieAssertionTests.java

@@ -16,15 +16,22 @@
 
 package org.springframework.test.web.servlet.samples.standalone.resultmatchers;
 
+import jakarta.servlet.http.Cookie;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.stereotype.Controller;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.servlet.HandlerInterceptor;
 import org.springframework.web.servlet.i18n.CookieLocaleResolver;
 import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;
 
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.hamcrest.CoreMatchers.anything;
+import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.startsWith;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
@@ -41,6 +48,8 @@ import static org.springframework.test.web.servlet.setup.MockMvcBuilders.standal
 public class CookieAssertionTests {
 
 	private static final String COOKIE_NAME = CookieLocaleResolver.DEFAULT_COOKIE_NAME;
+	private static final String COOKIE_WITH_ATTRIBUTES_NAME = "SecondCookie";
+	protected static final String SECOND_COOKIE_ATTRIBUTE = "COOKIE_ATTRIBUTE";
 
 	private MockMvc mockMvc;
 
@@ -50,9 +59,21 @@ public class CookieAssertionTests {
 		CookieLocaleResolver localeResolver = new CookieLocaleResolver();
 		localeResolver.setCookieDomain("domain");
 		localeResolver.setCookieHttpOnly(true);
+		localeResolver.setCookieSameSite("foo");
+
+		Cookie cookie = new Cookie(COOKIE_WITH_ATTRIBUTES_NAME, "value");
+		cookie.setAttribute("sameSite", "Strict"); //intentionally camelCase
+		cookie.setAttribute(SECOND_COOKIE_ATTRIBUTE, "there");
 
 		this.mockMvc = standaloneSetup(new SimpleController())
 				.addInterceptors(new LocaleChangeInterceptor())
+				.addInterceptors(new HandlerInterceptor() {
+					@Override
+					public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
+						response.addCookie(cookie);
+						return true;
+					}
+				})
 				.setLocaleResolver(localeResolver)
 				.defaultRequest(get("/").param("locale", "en_US"))
 				.alwaysExpect(status().isOk())
@@ -91,6 +112,26 @@ public class CookieAssertionTests {
 		this.mockMvc.perform(get("/")).andExpect(cookie().domain(COOKIE_NAME, "domain"));
 	}
 
+	@Test
+	void testSameSite() throws Exception {
+		this.mockMvc.perform(get("/")).andExpect(cookie()
+				.sameSite(COOKIE_NAME, "foo"));
+	}
+
+	@Test
+	void testSameSiteMatcher() throws Exception {
+		this.mockMvc.perform(get("/")).andExpect(cookie()
+				.sameSite(COOKIE_WITH_ATTRIBUTES_NAME, startsWith("Str")));
+	}
+
+	@Test
+	void testSameSiteNotEquals() throws Exception {
+		assertThatExceptionOfType(AssertionError.class).isThrownBy(() ->
+						this.mockMvc.perform(get("/")).andExpect(cookie()
+								.sameSite(COOKIE_WITH_ATTRIBUTES_NAME, "Str")))
+				.withMessage("Response cookie 'SecondCookie' attribute 'SameSite' expected:<Str> but was:<Strict>");
+	}
+
 	@Test
 	public void testVersion() throws Exception {
 		this.mockMvc.perform(get("/")).andExpect(cookie().version(COOKIE_NAME, 0));
@@ -111,6 +152,32 @@ public class CookieAssertionTests {
 		this.mockMvc.perform(get("/")).andExpect(cookie().httpOnly(COOKIE_NAME, true));
 	}
 
+	@Test
+	void testAttribute() throws Exception {
+		this.mockMvc.perform(get("/")).andExpect(cookie()
+				.attribute(COOKIE_WITH_ATTRIBUTES_NAME, SECOND_COOKIE_ATTRIBUTE, "there"));
+	}
+
+	@Test
+	void testAttributeMatcher() throws Exception {
+		this.mockMvc.perform(get("/")).andExpect(cookie()
+				.attribute(COOKIE_WITH_ATTRIBUTES_NAME, SECOND_COOKIE_ATTRIBUTE, is("there")));
+	}
+
+	@Test
+	void testAttributeNotPresent() {
+		assertThatExceptionOfType(AssertionError.class).isThrownBy(() -> this.mockMvc.perform(get("/"))
+						.andExpect(cookie().attribute(COOKIE_WITH_ATTRIBUTES_NAME, "randomAttribute", anything())))
+				.withMessage("Response cookie 'SecondCookie' doesn't have attribute 'randomAttribute'");
+	}
+
+	@Test
+	void testAttributeNotEquals() {
+		assertThatExceptionOfType(AssertionError.class).isThrownBy(() -> this.mockMvc.perform(get("/"))
+						.andExpect(cookie().attribute(COOKIE_WITH_ATTRIBUTES_NAME, SECOND_COOKIE_ATTRIBUTE, "foo")))
+				.withMessage("Response cookie 'SecondCookie' attribute 'COOKIE_ATTRIBUTE' expected:<foo> but was:<there>");
+	}
+
 
 	@Controller
 	private static class SimpleController {