improve test

tests/UnusedVariableTest.php

@@ -2142,20 +2142,23 @@ function foo(array $clips) : void {
                      * @param bool $b
                      */
                     function validate($b, string $source) : void {
-                        /**
-                         * @var bool|string $b
-                         */
+                        /** @var bool|string $b */
                         if (!is_bool($b)) {
                             $source = $b;
                             $b = false;
                         }
 
+                        /**
+                         * test to ensure $b is only type bool and not bool|string anymore
+                         * after we set $b = false; inside the condition above
+                         * @psalm-suppress TypeDoesNotContainType
+                         */
+                        if (!is_bool($b)) {
+                            echo "this should not happen"
+                        }
+
                         print_r($source);
                     }',
-                'assertions' => [
-                    '$b===' => 'bool',
-                ],
-                'ignored_issues' => ['UnusedVariable'],
             ],
             'implicitSpread' => [
                 'code' => '<?php