add compatibility with PHPUnit 11

Author: dmaicher

composer.json

@@ -3,7 +3,7 @@
     "description": "This package provides ArraySubset and related asserts once deprecated in PHPUnit 8",
     "type": "library",
     "require": {
-        "phpunit/phpunit": "^4.8.36 || ^5.7.21 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0",
+        "phpunit/phpunit": "^4.8.36 || ^5.7.21 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 || ^11.0",
         "php": "^5.4 || ^7.0 || ^8.0"
     },
     "license": "MIT",

src/Constraint/ArraySubset.php

@@ -10,6 +10,7 @@
 use PHPUnit\Framework\ExpectationFailedException;
 use PHPUnit\SebastianBergmann\Comparator\ComparisonFailure as Phar_ComparisonFailure;
 use SebastianBergmann\Comparator\ComparisonFailure;
+use SebastianBergmann\Exporter\Exporter;
 use SebastianBergmann\RecursionContext\InvalidArgumentException;
 use Traversable;
 
@@ -107,7 +108,9 @@ public function evaluate($other, string $description = '', bool $returnResult =
      */
     public function toString(): string
     {
-        return 'has the subset ' . $this->exporter()->export($this->subset);
+        $exporter = method_exists($this, 'exporter') ? $this->exporter() : new Exporter();
+
+        return 'has the subset ' . $exporter->export($this->subset);
     }
 
     /**