exchange/tests/Feature/ChinaBankSlipTest.php

<?php

namespace Tests\Feature;

use Tests\TestCase;
use Illuminate\Foundation\Testing\WithFaker;
use Illuminate\Foundation\Testing\RefreshDatabase;
use Illuminate\Support\Facades\Storage;
use Illuminate\Http\UploadedFile;
use Artisan;

class ChinaBankSlipTest extends TestCase
{
	protected $user;
    
	public function setUp(){
		parent::setUp();
		Artisan::call('db:seed');

		$this->user = factory(User::class)->create();
		$this->booking = factory(Booking::class)->create([
		    'user_id' => $this->user->id
		]);
		$this->user->attachRole(Role::Where('name','admin')->first());
	}

    public function testStore(){
    	Storage::fake('file');
    	$size_in_kb = 3072;    // 3072KB = 3MB
    	$china_bank_slips_path = UploadedFile::fake()->image('comp.jpg')->size($size_in_kb);
        
    	$response = 
		$this->postJson('api/booking/' . $user->id . 'upload-china-bankslip',[
			'china_bank_slips' => $china_bank_slips_path,
			'actual_transfer_amount' => '12',
			'details' => "123123",
			'date' => "123123"
		]);

		if(!file_exists($china_bank_slips_path) || $size_in_kb > 3072){
		    $response->assertStatus(400);    
		}
		else{
		    $response->assertSuccessful();
		}
    }
}