test: add test infrastructure for setup checks

Adds ExecMock, FileSystemMock, SetupCheckFunctions to mock system calls,
and updates bootstrap.php to load them.

Related issue: #6590
Type: Test

Checklist:
- [x] Create ExecMock class
- [x] Create FileSystemMock class
- [x] Create SetupCheckFunctions with file_exists and exec overrides
- [x] Update bootstrap.php to include new files

Author: guilhermercarvalho

tests/php/SetupCheckFunctions.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 LibreCode coop and contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Libresign\SetupCheck;
+
+if (!function_exists('OCA\Libresign\SetupCheck\file_exists')) {
+  function file_exists(string $filename): bool
+  {
+    if (array_key_exists($filename, FileSystemMock::$files)) {
+      return FileSystemMock::$files[$filename];
+    }
+    return \file_exists($filename);
+  }
+}
+
+if (!function_exists('OCA\Libresign\SetupCheck\exec')) {
+  function exec(string $command, &$output = null, &$result_code = null): string|false
+  {
+    if (array_key_exists($command, ExecMock::$commands)) {
+      $mock = ExecMock::$commands[$command];
+      $output = $mock['output'];
+      $result_code = $mock['result_code'];
+      return $output ? implode("\n", $output) : '';
+    }
+    return \exec($command, $output, $result_code);
+  }
+}

tests/php/Unit/SetupCheck/ExecMock.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 LibreCode coop and contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Libresign\SetupCheck;
+
+class ExecMock {
+    public static array $commands = [];
+}

tests/php/Unit/SetupCheck/FileSystemMock.php

@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\Libresign\SetupCheck;
+
+class FileSystemMock {
+    public static array $files = [];
+}

tests/php/bootstrap.php

@@ -17,6 +17,11 @@
 require_once __DIR__ . '/../../../../lib/base.php';
 require_once __DIR__ . '/../../../../tests/autoload.php';
 
+require_once __DIR__ . '/Unit/SetupCheck/FileSystemMock.php';
+require_once __DIR__ . '/Unit/SetupCheck/ExecMock.php';
+
+require_once __DIR__ . '/SetupCheckFunctions.php';
+
 \OC::$composerAutoloader->addPsr4('Test\\', OC::$SERVERROOT . '/tests/php/lib/', true);
 \OC::$composerAutoloader->addPsr4('Tests\\', OC::$SERVERROOT . '/tests/php/', true);
 \OC::$composerAutoloader->addPsr4('OCA\\Libresign\\Tests\\', __DIR__, true);