From 21ed8aad74ba575aca558109c6c86e670e6775e9 Mon Sep 17 00:00:00 2001
From: Sam Brannen <104798+sbrannen@users.noreply.github.com>
Date: Wed, 13 Mar 2024 10:47:34 +0100
Subject: [PATCH] Add missing test

---
 .../web/reactive/server/HeaderAssertionTests.java     | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/spring-test/src/test/java/org/springframework/test/web/reactive/server/HeaderAssertionTests.java b/spring-test/src/test/java/org/springframework/test/web/reactive/server/HeaderAssertionTests.java
index fcf647e6d46..6c0362831a4 100644
--- a/spring-test/src/test/java/org/springframework/test/web/reactive/server/HeaderAssertionTests.java
+++ b/spring-test/src/test/java/org/springframework/test/web/reactive/server/HeaderAssertionTests.java
@@ -105,6 +105,17 @@ class HeaderAssertionTests {
 						"[.*ISO-8859-1.*]"));
 	}
 
+	@Test
+	void valueMatchesWithNonexistentHeader() {
+		HttpHeaders headers = new HttpHeaders();
+		headers.setContentType(MediaType.parseMediaType("application/json;charset=UTF-8"));
+		HeaderAssertions assertions = headerAssertions(headers);
+
+		assertThatExceptionOfType(AssertionError.class)
+				.isThrownBy(() -> assertions.valueMatches("Content-XYZ", ".*ISO-8859-1.*"))
+				.withMessage("Response header 'Content-XYZ' not found");
+	}
+
 	@Test
 	void valuesMatch() {
 		HttpHeaders headers = new HttpHeaders();