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tests/ReturnModificationTest.php

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+<?php
+
+use PHPUnit\Framework\TestCase;
+use Tests\Aspects\ModifyingAspect;
+use Tests\Classes\ModifyingClass;
+
+final class ReturnModificationTest extends TestCase
+{
+    private ModifyingClass $instance;
+
+    protected function setUp(): void
+    {
+        $this->instance = new ModifyingClass();
+        ModifyingAspect::reset();
+    }
+
+    public function testAfterReturningOriginalValueDoesNotModifyResult(): void
+    {
+        ModifyingAspect::$modifier = fn($result) => $result;
+
+        $result = $this->instance->getValue();
+
+        $this->assertEquals(42, $result);
+    }
+
+    public function testAfterCanModifyIntegerResult(): void
+    {
+        ModifyingAspect::$modifier = fn($result) => $result * 2;
+
+        $result = $this->instance->getValue();
+
+        $this->assertEquals(84, $result);
+    }
+
+    public function testAfterCanModifyStringResult(): void
+    {
+        ModifyingAspect::$modifier = fn($result) => strtoupper($result);
+
+        $result = $this->instance->getString();
+
+        $this->assertEquals('ORIGINAL', $result);
+    }
+
+    public function testAfterCanIncrementIntegerResult(): void
+    {
+        ModifyingAspect::$modifier = fn($result) => $result + 100;
+
+        $result = $this->instance->getValue();
+
+        $this->assertEquals(142, $result);
+    }
+
+    public function testAfterCanModifyArrayResult(): void
+    {
+        ModifyingAspect::$modifier = fn($result) => array_merge($result, ['added' => 'new']);
+
+        $result = $this->instance->getArray();
+
+        $this->assertEquals(['key' => 'value', 'added' => 'new'], $result);
+    }
+
+    public function testAfterCanFilterArrayResult(): void
+    {
+        ModifyingAspect::$modifier = fn($result) => array_filter($result, fn($v) => $v !== 'value');
+
+        $result = $this->instance->getArray();
+
+        $this->assertEquals([], $result);
+    }
+
+    public function testMultipleCallsWithDifferentModifiers(): void
+    {
+        ModifyingAspect::$modifier = fn($result) => $result * 2;
+        $result1 = $this->instance->getValue();
+
+        ModifyingAspect::$modifier = fn($result) => $result + 10;
+        $result2 = $this->instance->getValue();
+
+        $this->assertEquals(84, $result1);
+        $this->assertEquals(52, $result2);
+    }
+
+    public function testNoModifierReturnsOriginalValue(): void
+    {
+        // ModifyingAspect::$modifier is null, so after() returns original value
+
+        $result = $this->instance->getValue();
+
+        $this->assertEquals(42, $result);
+    }
+}