Database [mybase] not configured Laravel 5

$langs = DB::connection('mybase')->select('select * from lang');

Database [mybase] not configured

$langs = DB::connection('mybase')

$langs = DB::connection('mysql')->select('select * from test_lang');

prefix'    => 'test_',

function arrPrint($arr){
echo "<pre>";
print_r($arr);
echp "</pre>"

'providers' => [
'Aoo\Providers\MyServiceProvider',
]

<?php
namespace App\Helpers;
 
Interface testInterface
{
    public function getTest();
}

<?php
namespace App\Helpers;
use App\Helpers\testInterface;
 
 
class testController implements testInterface
{
 
    public function getTest(){
        echo 123;
    }
}

<?php namespace App\Providers;
use Illuminate\Support\ServiceProvider;
use App\Helpers\testController;
 
class testServiceProvider extends ServiceProvider {
 
    /**
     * Bootstrap the application services.
     *
     * @return void
     */
    public function boot()
    {
        //
    }
 
    /**
     * Register the application services.
     *
     * @return void
     */
    public function register()
    {
        $this->app->bind('App\Helpers\testInterface', function(){
            return new testController();
        });
    }
 
}

<?php namespace App\Http\Controllers;
 
use Illuminate\Http\Request;
use App\Http\Requests;
use App\Helpers\testInterface;
class testController extends Controller {
 
    /*
    |--------------------------------------------------------------------------
    | Home Controller
    |--------------------------------------------------------------------------
    |
    | This controller renders your application's "dashboard" for users that
    | are authenticated. Of course, you are free to change or remove the
    | controller as you wish. It is just here to get your app started!
    |
    */
 
    /**
     * Create a new controller instance.
     *
     * @return void
     */
    public function __construct()
    {
        //$this->middleware('auth');
    }
 
    /**
     * Show the application dashboard to the user.
     *
     * @return Response
     */
    public function index() {
        return view('index');
    }
 
    public function perehod(testInterface $tests){
        $test = $tests->getTest();
        return view('perehod', array("tests" => $tests));
    }
 
}

BindingResolutionException in Container.php line 788:
Target [App\Helpers\testInterface] is not instantiable.

use App\Helpers\testInterface;

        for($i = 0; $i < count($array_letters); $i++){
            $array_images[] = DB::table('symbol')
                ->where('symbol_name', '=', $array_letters[$i])
                ->select('symbol_id')->first();
 
        }

Array
(
    [0] => stdClass Object
        (
            [symbol_id] => 21
        )
 
    [1] => stdClass Object
        (
            [symbol_id] => 28
        )
 
    [2] => stdClass Object
        (
            [symbol_id] => 3
        )
 
    [3] => stdClass Object
        (
            [symbol_id] => 28
        )
 
    [4] => stdClass Object
        (
            [symbol_id] => 21
        )
 
    [5] => stdClass Object
        (
            [symbol_id] => 3
        )
 
)

Array
(
    [0] =>  21
    [1] =>  28
    [2] =>  3
    [3] =>  28
    [4] =>  21
    [5] =>  3
)

DB::table('symbol')
       ->whereIn('symbol_name', $array_letters)
       ->pluck('symbol_id')
       ->all();

Call to a member function all() on string

dd(DB::table('symbol')
       ->whereIn('symbol_name', $array_letters)
       ->pluck('symbol_id'));

DB::table('symbol')
       ->whereIn('symbol_name', $array_letters)
       ->lists('symbol_id');

Array ( [0] => 3 [1] => 21 [2] => 28 )

Call to a member function all() on array