qa: add failing test for issue #8787

Signed-off-by: Maximilian Bösing <2189546+boesing@users.noreply.github.com>

tests/ArrayAssignmentTest.php

@@ -2024,6 +2024,29 @@ class ArrayAssignmentTest extends TestCase
                     '$b===' => 'list{0, 1, 2}',
                 ],
             ],
+            'appendValuesToMap' => [
+                'code' => '<?php
+                    /**
+                     * @return array{foo:numeric-string}&array<non-empty-string,non-empty-string>
+                     */
+                    function defaultQueryParams(): array
+                    {
+                        return [
+                           "foo" => "123",
+                           "bar" => "baz",
+                        ];
+                    }
+
+                    /**
+                     * @return array<non-empty-string, non-empty-string>
+                     */
+                    function getQueryParams(): array
+                    {
+                        $queryParams = defaultQueryParams();
+                        $queryParams["a"] = "zzz";
+                        return $queryParams;
+                    }',
+            ],
         ];
     }