feat: allow PHPUnit 10-12

Author: Chris8934

CHANGELOG.md

@@ -6,6 +6,12 @@ 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).
 
+
+## [3.1.2] - 2025-11-11
+
+- Allow PHPUnit > 9
+- Removed PhpUnitBackwardCompatibleTrait
+
 ## [3.1.1] - 2024-09-01
 
 - Switched to `httpbin.org` for tests now that its fixed. (Reverts [#56](https://github.com/php-http/client-integration-tests/pull/56))

src/HttpBaseTest.php

@@ -10,8 +10,6 @@
 
 abstract class HttpBaseTest extends TestCase
 {
-    use PhpUnitBackwardCompatibleTrait;
-
     /**
      * @var string
      */
@@ -223,7 +221,7 @@ protected function assertResponse(ResponseInterface $response, array $options =
         if (null === $options['body']) {
             $this->assertEmpty($response->getBody()->__toString());
         } else {
-            self::assertStringContainsStringCompatible($options['body'], $response->getBody()->__toString());
+            self::assertStringContainsString($options['body'], $response->getBody()->__toString());
         }
     }
 

src/HttpFeatureTest.php

@@ -9,8 +9,6 @@
 
 abstract class HttpFeatureTest extends TestCase
 {
-    use PhpUnitBackwardCompatibleTrait;
-
     /**
      * @var MessageFactory
      */
@@ -143,7 +141,7 @@ public function testEncoding()
         $response = $this->createClient()->sendRequest($request);
 
         $this->assertSame(200, $response->getStatusCode());
-        $this->assertStringContainsStringCompatible('€', $response->getBody()->__toString());
+        $this->assertStringContainsString('€', $response->getBody()->__toString());
     }
 
     /**
@@ -159,7 +157,7 @@ public function testGzip()
         $response = $this->createClient()->sendRequest($request);
 
         $this->assertSame(200, $response->getStatusCode());
-        $this->assertStringContainsStringCompatible('gzip', $response->getBody()->__toString());
+        $this->assertStringContainsString('gzip', $response->getBody()->__toString());
     }
 
     /**
@@ -175,7 +173,7 @@ public function testDeflate()
         $response = $this->createClient()->sendRequest($request);
 
         $this->assertSame(200, $response->getStatusCode());
-        $this->assertStringContainsStringCompatible('deflate', $response->getBody()->__toString());
+        $this->assertStringContainsString('deflate', $response->getBody()->__toString());
     }
 
     /**