From 9c5e608f501ca127b34ca7535f57aec13eec8e36 Mon Sep 17 00:00:00 2001
From: Andy Wilkinson <andy.wilkinson@broadcom.com>
Date: Wed, 16 Apr 2025 14:44:45 +0100
Subject: [PATCH] Polish "Fix parameter replacement when message matches its
 code"

See gh-45212
---
 .../MessageSourceMessageInterpolatorTests.java    | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/validation/MessageSourceMessageInterpolatorTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/validation/MessageSourceMessageInterpolatorTests.java
index 2ce0345604..63e427511c 100644
--- a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/validation/MessageSourceMessageInterpolatorTests.java
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/validation/MessageSourceMessageInterpolatorTests.java
@@ -62,8 +62,21 @@ class MessageSourceMessageInterpolatorTests {
 	void interpolateWhenParametersAreUnknownUsingCodeAsDefaultShouldLeaveThemUnchanged() {
 		this.messageSource.setUseCodeAsDefaultMessage(true);
 		this.messageSource.addMessage("top", Locale.getDefault(), "{child}+{child}");
+		assertThat(this.interpolator.interpolate("{foo}{top}{bar}", this.context))
+			.isEqualTo("{foo}{child}+{child}{bar}");
+	}
+
+	@Test
+	void interpolateShouldReplaceParameterThatReferencesAMessageThatMatchesItsCode() {
 		this.messageSource.addMessage("foo", Locale.getDefault(), "foo");
-		assertThat(this.interpolator.interpolate("{foo}{top}{bar}", this.context)).isEqualTo("foo{child}+{child}{bar}");
+		assertThat(this.interpolator.interpolate("{foo}", this.context)).isEqualTo("foo");
+	}
+
+	@Test
+	void interpolateUsingCodeAsDefaultShouldReplaceParameterThatReferencesAMessageThatMatchesItsCode() {
+		this.messageSource.setUseCodeAsDefaultMessage(true);
+		this.messageSource.addMessage("foo", Locale.getDefault(), "foo");
+		assertThat(this.interpolator.interpolate("{foo}", this.context)).isEqualTo("foo");
 	}
 
 	@Test