Laravel 5.1 Class 'app\Http\Controllers\Controller' not found

I'm quite new to Laravel and when I am going through a tutorial, I encountered this error. This is my code in 'testController.php'.

<?php

namespace app\Http\Controllers;

use app\Http\Controllers\Controller;

class testController extends \app\Http\Controllers\Controller {

public function getAbout()
{
    return view('Learning.about') ;
}

public function getHome()
{
    return view('Learning.index');
}

}

And this is my 'routes.php'.

<?php
Route::get('test', [
   'as' => 'test', 
   'uses' => 'testController@getHome',
]);

Route::get('about', [
    'as' => 'about', 
    'uses' => 'testController@getAbout',
]);

I would be really grateful if somebody could lead me to a solution and probably explain the cause as well to refrain from such error.

Thank You.

via Chebli Mohamed