diff --git a/spring-test/src/main/java/org/springframework/mock/web/MockCookie.java b/spring-test/src/main/java/org/springframework/mock/web/MockCookie.java
index d9b7e8c5f1..b70b3ea606 100644
--- a/spring-test/src/main/java/org/springframework/mock/web/MockCookie.java
+++ b/spring-test/src/main/java/org/springframework/mock/web/MockCookie.java
@@ -22,7 +22,7 @@ import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
- * Extension of {@code Cookie} with extra directives, as defined in
+ * Extension of {@code Cookie} with extra attributes, as defined in
  * <a href="https://tools.ietf.org/html/rfc6265">RFC 6265</a>.
  *
  * @author Vedran Pavic
@@ -75,40 +75,41 @@ public class MockCookie extends Cookie {
 	 */
 	public static MockCookie parse(String setCookieHeader) {
 		String[] cookieParts = setCookieHeader.split("\\s*=\\s*", 2);
-		Assert.isTrue(cookieParts.length == 2, "Invalid Set-Cookie header value");
+		Assert.isTrue(cookieParts.length == 2, () -> "Invalid Set-Cookie header value '" + setCookieHeader + "'");
 
 		String name = cookieParts[0];
-		String[] valueAndDirectives = cookieParts[1].split("\\s*;\\s*", 2);
-		String value = valueAndDirectives[0];
-		String[] directives = valueAndDirectives.length > 1 ? valueAndDirectives[1].split("\\s*;\\s*") : new String[0];
+		String[] valueAndAttributes = cookieParts[1].split("\\s*;\\s*", 2);
+		String value = valueAndAttributes[0];
+		String[] attributes = valueAndAttributes.length > 1 ? valueAndAttributes[1].split("\\s*;\\s*") : new String[0];
 
 		MockCookie cookie = new MockCookie(name, value);
-		for (String directive : directives) {
-			if (directive.startsWith("Domain")) {
-				cookie.setDomain(extractDirectiveValue(directive));
+		for (String attribute : attributes) {
+			if (attribute.startsWith("Domain")) {
+				cookie.setDomain(extractAttributeValue(attribute, setCookieHeader));
 			}
-			else if (directive.startsWith("Max-Age")) {
-				cookie.setMaxAge(Integer.parseInt(extractDirectiveValue(directive)));
+			else if (attribute.startsWith("Max-Age")) {
+				cookie.setMaxAge(Integer.parseInt(extractAttributeValue(attribute, setCookieHeader)));
 			}
-			else if (directive.startsWith("Path")) {
-				cookie.setPath(extractDirectiveValue(directive));
+			else if (attribute.startsWith("Path")) {
+				cookie.setPath(extractAttributeValue(attribute, setCookieHeader));
 			}
-			else if (directive.startsWith("Secure")) {
+			else if (attribute.startsWith("Secure")) {
 				cookie.setSecure(true);
 			}
-			else if (directive.startsWith("HttpOnly")) {
+			else if (attribute.startsWith("HttpOnly")) {
 				cookie.setHttpOnly(true);
 			}
-			else if (directive.startsWith("SameSite")) {
-				cookie.setSameSite(extractDirectiveValue(directive));
+			else if (attribute.startsWith("SameSite")) {
+				cookie.setSameSite(extractAttributeValue(attribute, setCookieHeader));
 			}
 		}
 		return cookie;
 	}
 
-	private static String extractDirectiveValue(String directive) {
-		String[] nameAndValue = directive.split("=");
-		Assert.isTrue(nameAndValue.length == 2, () -> "No value in directive: '" + directive + "'");
+	private static String extractAttributeValue(String attribute, String header) {
+		String[] nameAndValue = attribute.split("=");
+		Assert.isTrue(nameAndValue.length == 2,
+				() -> "No value in attribute '" + nameAndValue[0] + "' for Set-Cookie header '" + header + "'");
 		return nameAndValue[1];
 	}
 
diff --git a/spring-test/src/test/java/org/springframework/mock/web/MockCookieTests.java b/spring-test/src/test/java/org/springframework/mock/web/MockCookieTests.java
index 7af2c8a9f3..77c0be4b7f 100644
--- a/spring-test/src/test/java/org/springframework/mock/web/MockCookieTests.java
+++ b/spring-test/src/test/java/org/springframework/mock/web/MockCookieTests.java
@@ -16,7 +16,9 @@
 
 package org.springframework.mock.web;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import static org.junit.Assert.*;
 
@@ -24,8 +26,13 @@ import static org.junit.Assert.*;
  * Unit tests for {@link MockCookie}.
  *
  * @author Vedran Pavic
+ * @author Sam Brannen
+ * @since 5.1
  */
 public class MockCookieTests {
+	
+	@Rule
+	public ExpectedException exception = ExpectedException.none();
 
 	@Test
 	public void constructCookie() {
@@ -58,9 +65,20 @@ public class MockCookieTests {
 		assertEquals("Lax", cookie.getSameSite());
 	}
 
-	@Test(expected = IllegalArgumentException.class)
+	@Test
 	public void parseInvalidHeader() {
-		MockCookie.parse("invalid");
+		exception.expect(IllegalArgumentException.class);
+		exception.expectMessage("Invalid Set-Cookie header value 'BOOM'");
+		MockCookie.parse("BOOM");
+	}
+
+	@Test
+	public void parseInvalidAttribute() {
+		String header = "foo=bar; Path=";
+
+		exception.expect(IllegalArgumentException.class);
+		exception.expectMessage("No value in attribute 'Path' for Set-Cookie header '" + header + "'");
+		MockCookie.parse(header);
 	}
 
 }