Add failing test case

tests/Twig/Runtime/IconRuntimeTest.php

@@ -248,4 +248,11 @@ class IconRuntimeTest extends TestCase
         $this->expectException(\InvalidArgumentException::class);
         $this->icon->renderIcon(['icon' => self::ICON, 'fake-key-should-throw' => null]);
     }
+
+    public function testStrokeCurrentColorInstancesAreRemoved(): void
+    {
+        $needle = 'stroke="currentColor"';
+        $contents = $this->icon->renderIcon(['icon' => self::ICON]);
+        $this->assertStringNotContainsString($needle, $contents);
+    }
 }