我在窗口 7 上安装了 Laravel，但收到错误消息

我在运行演示文件时安装了 laravel，它给了我错误消息。 错误消息是：-

     Class 'Illuminate'Foundation'Testing'TestCase' not found in D:'xampp'htdocs'laravel'tests'TestCase.php on line 4

为了解决这个问题，我尝试在命令提示符上运行phpunit应用程序/测试/命令，但没有任何反应。 我的作曲家.json文件是：--

  {
   "name": "laravel/laravel",
   "description": "The Laravel Framework.",
   "keywords": ["framework", "laravel"],
   "license": "MIT",
   "type": "project",
   "require": {
    "php": ">=5.5.9",
    "laravel/framework": "5.2.*"
  },
"require-dev": {
    "fzaninotto/faker": "~1.4",
    "mockery/mockery": "0.9.*",
    "phpunit/phpunit": "~4.0",
    "symfony/css-selector": "2.8.*|3.0.*",
    "symfony/dom-crawler": "2.8.*|3.0.*"
},
"autoload": {
    "classmap": [
        "database"
    ],
    "psr-4": {
        "App''": "app/"
    }
},
"autoload-dev": {
    "classmap": [
        "tests/TestCase.php"
    ]
},
"scripts": {
    "post-root-package-install": [
        "php -r '"copy('.env.example', '.env');'""
    ],
    "post-create-project-cmd": [
        "php artisan key:generate"
    ],
    "post-install-cmd": [
        "Illuminate''Foundation''ComposerScripts::postInstall",
        "php artisan optimize"
    ],
    "post-update-cmd": [
        "Illuminate''Foundation''ComposerScripts::postUpdate",
        "php artisan optimize"
    ]
},
"config": {
    "preferred-install": "dist"
}

}