From b9a59853fa9bca1040688b51873bb4af1a5975b9 Mon Sep 17 00:00:00 2001
From: rstoyanchev <rossen.stoyanchev@broadcom.com>
Date: Fri, 20 Feb 2026 13:38:51 +0000
Subject: [PATCH] Use case-insensitive comparator in HttpHeadersAssert

Closes gh-36349
---
 .../org/springframework/test/http/HttpHeadersAssert.java    | 2 ++
 .../servlet/assertj/AbstractHttpServletResponseAssert.java  | 6 ++----
 .../springframework/test/http/HttpHeadersAssertTests.java   | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/spring-test/src/main/java/org/springframework/test/http/HttpHeadersAssert.java b/spring-test/src/main/java/org/springframework/test/http/HttpHeadersAssert.java
index 3c41f4d9447..d2b4cdff001 100644
--- a/spring-test/src/main/java/org/springframework/test/http/HttpHeadersAssert.java
+++ b/spring-test/src/main/java/org/springframework/test/http/HttpHeadersAssert.java
@@ -47,7 +47,9 @@ public class HttpHeadersAssert extends AbstractObjectAssert<HttpHeadersAssert, H
 	public HttpHeadersAssert(HttpHeaders actual) {
 		super(actual, HttpHeadersAssert.class);
 		as("HTTP headers");
+		// Use case-insensitive comparator until https://github.com/assertj/assertj/issues/4157
 		this.namesAssert = Assertions.assertThat(actual.headerNames())
+				.usingElementComparator(String.CASE_INSENSITIVE_ORDER)
 				.as("HTTP header names");
 	}
 
diff --git a/spring-test/src/main/java/org/springframework/test/web/servlet/assertj/AbstractHttpServletResponseAssert.java b/spring-test/src/main/java/org/springframework/test/web/servlet/assertj/AbstractHttpServletResponseAssert.java
index 9cd35c25971..6dd97ef7564 100644
--- a/spring-test/src/main/java/org/springframework/test/web/servlet/assertj/AbstractHttpServletResponseAssert.java
+++ b/spring-test/src/main/java/org/springframework/test/web/servlet/assertj/AbstractHttpServletResponseAssert.java
@@ -31,8 +31,6 @@ import org.springframework.http.HttpStatus.Series;
 import org.springframework.http.MediaType;
 import org.springframework.test.http.HttpHeadersAssert;
 import org.springframework.test.http.MediaTypeAssert;
-import org.springframework.util.LinkedMultiValueMap;
-import org.springframework.util.MultiValueMap;
 import org.springframework.util.function.SingletonSupplier;
 
 /**
@@ -65,9 +63,9 @@ public abstract class AbstractHttpServletResponseAssert<R extends HttpServletRes
 	}
 
 	private static HttpHeaders getHttpHeaders(HttpServletResponse response) {
-		MultiValueMap<String, String> headers = new LinkedMultiValueMap<>();
+		HttpHeaders headers = new HttpHeaders();
 		response.getHeaderNames().forEach(name -> headers.put(name, new ArrayList<>(response.getHeaders(name))));
-		return new HttpHeaders(headers);
+		return headers;
 	}
 
 	/**
diff --git a/spring-test/src/test/java/org/springframework/test/http/HttpHeadersAssertTests.java b/spring-test/src/test/java/org/springframework/test/http/HttpHeadersAssertTests.java
index 8883299810d..16c8cbb1df1 100644
--- a/spring-test/src/test/java/org/springframework/test/http/HttpHeadersAssertTests.java
+++ b/spring-test/src/test/java/org/springframework/test/http/HttpHeadersAssertTests.java
@@ -161,8 +161,8 @@ class HttpHeadersAssertTests {
 	@Test
 	void hasValueWithStringMatch() {
 		HttpHeaders headers = new HttpHeaders();
-		headers.addAll("header", List.of("a", "b", "c"));
-		assertThat(headers).hasValue("header", "a");
+		headers.addAll("Header", List.of("a", "b", "c"));
+		assertThat(headers).hasValue("hEADer", "a");
 	}
 
 	@Test