Fix PHPUnit 9.6 deprecations

Author: derrabus

Tests/ExpressionLanguageTest.php

@@ -311,12 +311,25 @@ public function testNullSafeEvaluateFails($expression, $foo, $message)
     /**
      * @dataProvider provideInvalidNullSafe
      */
-    public function testNullSafeCompileFails($expression, $foo)
+    public function testNullSafeCompileFails($expression)
     {
         $expressionLanguage = new ExpressionLanguage();
 
-        $this->expectWarning();
-        eval(sprintf('return %s;', $expressionLanguage->compile($expression, ['foo' => 'foo'])));
+        $this->expectException(\ErrorException::class);
+
+        set_error_handler(static function (int $errno, string $errstr, string $errfile = null, int $errline = null): bool {
+            if ($errno & (\E_WARNING | \E_USER_WARNING)) {
+                throw new \ErrorException($errstr, 0, $errno, $errfile, $errline);
+            }
+
+            return false;
+        });
+
+        try {
+            eval(sprintf('return %s;', $expressionLanguage->compile($expression, ['foo' => 'foo'])));
+        } finally {
+            restore_error_handler();
+        }
     }
 
     public static function provideInvalidNullSafe()