AG-43382: fixed incorrect coding when creating patch via spawn process

Squashed commit of the following:

commit 6cc97ae
Author: Dmitriy Seregin <d.seregin@adguard.com>
Date:   Wed Jun 18 15:55:04 2025 +0300

    update changelog

commit 1a8b6cd
Author: Dmitriy Seregin <d.seregin@adguard.com>
Date:   Wed Jun 18 15:51:57 2025 +0300

    AG-43382: fixed incorrect coding when creating
    patch via spawn process

Author: 105th

CHANGELOG.md

@@ -5,6 +5,15 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.1.2] - 2025-06-18
+
+## Fixed
+
+- Incorrect coding when preparing a patch [FiltersRegistry#1091].
+
+[1.1.2]: https://github.com/AdguardTeam/DiffBuilder/compare/v1.1.1...v1.1.2
+[FiltersRegistry#1091]: https://github.com/AdguardTeam/FiltersRegistry/issues/1091
+
 ## [1.1.1] - 2025-06-09
 
 ### Changed

package.json

@@ -1,6 +1,6 @@
 {
     "name": "@adguard/diff-builder",
-    "version": "1.1.1",
+    "version": "1.1.2",
     "description": "A tool for generating differential updates for filter lists.",
     "repository": {
         "type": "git",

src/common/spawn-diff.ts

@@ -14,6 +14,10 @@ export const spawnDiff = (oldFilePath: string, newFilePath: string): Promise<str
         // '-n' option is used to build a patch in RCS format
         const diffProcess = spawn('diff', ['-n', oldFilePath, newFilePath]);
 
+        // Set encoding for stdout and stderr to 'utf-8'
+        diffProcess.stdout.setEncoding('utf-8');
+        diffProcess.stderr.setEncoding('utf-8');
+
         let output = '';
         let errorOutput = '';
 

tests/diff-builder.test.ts

@@ -16,6 +16,9 @@ import {
     FILE_7,
     FILE_7_8_PATCH,
     FILE_8,
+    FILE_WITH_EXTENDED_SYMBOLS_OLD,
+    FILE_WITH_EXTENDED_SYMBOLS_NEW,
+    FILE_WITH_EXTENDED_SYMBOLS_PATCH,
 } from './stubs/random-files';
 import { FILTER_1_V_1_0_0, FILTER_1_V_1_0_1, PATCH_1_1_0_0 } from './stubs/simple';
 import { FILTER_2_V_1_0_0, FILTER_2_V_1_0_1, PATCH_2_1_0_0 } from './stubs/validation';
@@ -76,6 +79,7 @@ describe('check diff-builder', () => {
             [FILE_3, FILE_4, FILE_3_4_PATCH],
             [FILE_5, FILE_6, FILE_5_6_PATCH],
             [FILE_7, FILE_8, FILE_7_8_PATCH],
+            [FILE_WITH_EXTENDED_SYMBOLS_OLD, FILE_WITH_EXTENDED_SYMBOLS_NEW, FILE_WITH_EXTENDED_SYMBOLS_PATCH],
         ];
 
         it.each(cases)('creates patch', async (