test(Unit): Add GithubCopilotCliGeneratorTest

- Add new file `GithubCopilotCliGeneratorTest.php` to `tests/Unit/Generators` directory
- Add PHP code to the file
- Configure `generators.github_copilot_cli.binary` to `github-copilot-cli`
- Generate error using `GeneratorManager` driver
- Expect `ProcessFailedException` to be thrown

Author: ityaozm@gmail.com

tests/Unit/Generators/GithubCopilotCliGeneratorTest.php

@@ -0,0 +1,30 @@
+<?php
+
+/** @noinspection AnonymousFunctionStaticInspection */
+/** @noinspection JsonEncodingApiUsageInspection */
+/** @noinspection NullPointerExceptionInspection */
+/** @noinspection PhpUnhandledExceptionInspection */
+/** @noinspection PhpUnused */
+/** @noinspection PhpUnusedAliasInspection */
+/** @noinspection StaticClosureCanBeUsedInspection */
+
+declare(strict_types=1);
+
+/**
+ * This file is part of the guanguans/ai-commit.
+ *
+ * (c) guanguans <ityaozm@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled.
+ */
+
+use App\GeneratorManager;
+use Symfony\Component\Process\Exception\ProcessFailedException;
+
+beforeEach(function (): void {
+});
+
+it('throws `ProcessFailedException`', function (): void {
+    config('ai-commit')->set('generators.github_copilot_cli.binary', 'github-copilot-cli');
+    expect(app(GeneratorManager::class)->driver('github_copilot_cli'))->generate('error');
+})->group(__DIR__, __FILE__)->throws(ProcessFailedException::class);