feat: allow PHPUnit 10-12

Author: Chris8934

CHANGELOG.md

@@ -10,7 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [3.1.2] - 2025-11-11
 
 - Allow PHPUnit > 9
-- Removed PhpUnitBackwardCompatibleTrait
+- Deprecate PhpUnitBackwardCompatibleTrait
 
 ## [3.1.1] - 2024-09-01
 

src/PhpUnitBackwardCompatibleTrait.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Http\Client\Tests;
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @deprecated
+ */
+trait PhpUnitBackwardCompatibleTrait
+{
+    public static function assertStringContainsString(string $needle, string $haystack, string $message = ''): void
+    {
+        // For supporting both phpunit 7 and 8 without display any deprecation.
+        if (method_exists(TestCase::class, 'assertStringContainsString')) {
+            parent::assertStringContainsString($needle, $haystack, $message);
+        } else {
+            parent::assertContains($needle, $haystack, $message);
+        }
+    }
+}