From fafe72523586dc28d3cab91e2e86beab33ece55f Mon Sep 17 00:00:00 2001
From: Copilot <198982749+Copilot@users.noreply.github.com>
Date: Mon, 17 Nov 2025 06:16:26 +0000
Subject: [PATCH] Add test for BOM character preservation in VSBuffer (issue
 #251527) (#277608)

* Initial plan

* Add test for issue #251527 - BOM character preservation in VSBuffer

Co-authored-by: bpasero <900690+bpasero@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: bpasero <900690+bpasero@users.noreply.github.com>
---
 src/vs/base/test/common/buffer.test.ts | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/vs/base/test/common/buffer.test.ts b/src/vs/base/test/common/buffer.test.ts
index f4d9c5a04e4..9109d4cdb1b 100644
--- a/src/vs/base/test/common/buffer.test.ts
+++ b/src/vs/base/test/common/buffer.test.ts
@@ -19,6 +19,20 @@ suite('Buffer', () => {
 		assert.deepStrictEqual(buffer.toString(), 'hi');
 	});
 
+	test('issue #251527 - VSBuffer#toString preserves BOM character in filenames', () => {
+		// BOM character (U+FEFF) is a zero-width character that was being stripped
+		// when deserializing messages in the IPC layer. This test verifies that
+		// the BOM character is preserved when using VSBuffer.toString().
+		const bomChar = '\uFEFF';
+		const filename = `${bomChar}c.txt`;
+		const buffer = VSBuffer.fromString(filename);
+		const result = buffer.toString();
+
+		// Verify the BOM character is preserved
+		assert.strictEqual(result, filename);
+		assert.strictEqual(result.charCodeAt(0), 0xFEFF);
+	});
+
 	test('bufferToReadable / readableToBuffer', () => {
 		const content = 'Hello World';
 		const readable = bufferToReadable(VSBuffer.fromString(content));