From c26029c26b7cdcf0bde7bc7d4a07bc38927dce50 Mon Sep 17 00:00:00 2001
From: Sam Brannen <104798+sbrannen@users.noreply.github.com>
Date: Mon, 15 Jun 2026 15:25:59 +0200
Subject: [PATCH] Use "instanceof pattern matching" in
 WebSocketExtension.equals()

---
 .../web/socket/WebSocketExtension.java        |  7 +-
 .../web/socket/WebSocketExtensionTests.java   | 97 +++++++++++++++++++
 2 files changed, 99 insertions(+), 5 deletions(-)

diff --git a/spring-websocket/src/main/java/org/springframework/web/socket/WebSocketExtension.java b/spring-websocket/src/main/java/org/springframework/web/socket/WebSocketExtension.java
index c8a62ccabe7..7fbc342ce59 100644
--- a/spring-websocket/src/main/java/org/springframework/web/socket/WebSocketExtension.java
+++ b/spring-websocket/src/main/java/org/springframework/web/socket/WebSocketExtension.java
@@ -104,11 +104,8 @@ public class WebSocketExtension {
 		if (this == other) {
 			return true;
 		}
-		if (other == null || !(other instanceof WebSocketExtension)) {
-			return false;
-		}
-		WebSocketExtension otherExt = (WebSocketExtension) other;
-		return (this.name.equals(otherExt.name) && this.parameters.equals(otherExt.parameters));
+		return (other instanceof WebSocketExtension that &&
+				this.name.equals(that.name) && this.parameters.equals(that.parameters));
 	}
 
 	@Override
diff --git a/spring-websocket/src/test/java/org/springframework/web/socket/WebSocketExtensionTests.java b/spring-websocket/src/test/java/org/springframework/web/socket/WebSocketExtensionTests.java
index 6dbaeaac167..92971cb7969 100644
--- a/spring-websocket/src/test/java/org/springframework/web/socket/WebSocketExtensionTests.java
+++ b/spring-websocket/src/test/java/org/springframework/web/socket/WebSocketExtensionTests.java
@@ -17,7 +17,9 @@
 package org.springframework.web.socket;
 
 import java.util.List;
+import java.util.Map;
 
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -27,6 +29,7 @@ import static org.assertj.core.api.Assertions.entry;
  * Test fixture for {@link WebSocketExtension}.
  *
  * @author Brian Clozel
+ * @author Sam Brannen
  */
 class WebSocketExtensionTests {
 
@@ -51,4 +54,98 @@ class WebSocketExtensionTests {
 				.containsExactly("x-foo-extension", "x-bar-extension");
 	}
 
+
+	@Nested
+	class EqualsTests {
+
+		@Test
+		void equalToSelf() {
+			WebSocketExtension extension = new WebSocketExtension("x-test");
+			assertThat(extension).isEqualTo(extension);
+		}
+
+		@Test
+		void notEqualToNull() {
+			WebSocketExtension extension = new WebSocketExtension("x-test");
+			assertThat(extension).isNotEqualTo(null);
+		}
+
+		@Test
+		void notEqualToDifferentType() {
+			WebSocketExtension extension = new WebSocketExtension("x-test");
+			assertThat(extension).isNotEqualTo("x-test");
+		}
+
+		@Test
+		void equalWithSameName() {
+			assertThat(new WebSocketExtension("x-test"))
+					.isEqualTo(new WebSocketExtension("x-test"));
+		}
+
+		@Test
+		void equalWithSameNameAndParameter() {
+			assertThat(new WebSocketExtension("x-test", Map.of("foo", "bar")))
+					.isEqualTo(new WebSocketExtension("x-test", Map.of("foo", "bar")));
+		}
+
+		@Test
+		void equalWithSameNameAndMultipleParameters() {
+			assertThat(new WebSocketExtension("x-test", Map.of("foo", "1", "bar", "2")))
+					.isEqualTo(new WebSocketExtension("x-test", Map.of("foo", "1", "bar", "2")));
+		}
+
+		@Test
+		void notEqualWithDifferentName() {
+			assertThat(new WebSocketExtension("x-foo"))
+					.isNotEqualTo(new WebSocketExtension("x-bar"));
+		}
+
+		@Test
+		void notEqualWithDifferentNameCase() {
+			assertThat(new WebSocketExtension("x-test"))
+					.isNotEqualTo(new WebSocketExtension("X-TEST"));
+		}
+
+		@Test
+		void notEqualWithDifferentParameterValue() {
+			assertThat(new WebSocketExtension("x-test", Map.of("foo", "bar")))
+					.isNotEqualTo(new WebSocketExtension("x-test", Map.of("foo", "baz")));
+		}
+
+		@Test
+		void notEqualWithDifferentParameterKey() {
+			assertThat(new WebSocketExtension("x-test", Map.of("foo", "bar")))
+					.isNotEqualTo(new WebSocketExtension("x-test", Map.of("baz", "bar")));
+		}
+
+		@Test
+		void notEqualWithDifferentParameterCount() {
+			assertThat(new WebSocketExtension("x-test", Map.of("foo", "bar")))
+					.isNotEqualTo(new WebSocketExtension("x-test", Map.of("foo", "bar", "baz", "qux")));
+		}
+	}
+
+
+	@Nested
+	class HashCodeTests {
+
+		@Test
+		void sameHashCodeForEqualExtensions() {
+			assertThat(new WebSocketExtension("x-test", Map.of("foo", "bar")).hashCode())
+					.isEqualTo(new WebSocketExtension("x-test", Map.of("foo", "bar")).hashCode());
+		}
+
+		@Test
+		void differentHashCodeForDifferentNames() {
+			assertThat(new WebSocketExtension("x-foo").hashCode())
+					.isNotEqualTo(new WebSocketExtension("x-bar").hashCode());
+		}
+
+		@Test
+		void differentHashCodeForDifferentParameterValues() {
+			assertThat(new WebSocketExtension("x-test", Map.of("foo", "bar")).hashCode())
+					.isNotEqualTo(new WebSocketExtension("x-test", Map.of("foo", "baz")).hashCode());
+		}
+	}
+
 }