Test.php

<?php

namespace Wolfe\Tests;

use PHPUnit_Framework_TestCase;
use Slim\App;
use Slim\Http\Environment;
use Slim\Http\Headers;
use Slim\Http\Request;
use Slim\Http\RequestBody;
use Slim\Http\Response;
use Slim\Http\UploadedFile;
use Slim\Http\Uri;
use Wolfe\Loader\Kernel;

class AbstractFunctionalTest extends PHPUnit_Framework_TestCase
{

    /** @var App $app */
    protected $app;

    /** @var Request $request */
    protected $request;

    /** @var Response $response */
    protected $response;

    public function setUp()
    {
        $app = new App();

        $kernel = new Kernel($app, $app->getContainer());
        $kernel->registerServices();
        $kernel->registerRoutes();

        $this->app = $app;
    }

    public function setupRequest($url, $method, $request, $files)
    {
        $env = Environment::mock([
            'REQUEST_URI' => $url,
            'REQUEST_METHOD' => $method,
        ]);
        $uri = Uri::createFromEnvironment($env);
        $headers = Headers::createFromEnvironment($env);
        $cookies = [];
        $serverParams = $env->all();
        $body = new RequestBody();
        $this->request = new Request($method, $uri, $headers, $cookies, $serverParams, $body, $files);
        $this->response = new Response();

        /*if (!is_null($files)) {
            $this->request->withUploadedFiles($files);
        }

        if (!is_null($request)) {
            $this->request->withQueryParams($request);
        }*/

        $app = $this->app;

        return $app($this->request, $this->response);
    }

    public function get($url)
    {
        return $this->setupRequest($url, 'GET', null, null);
    }

    public function post($url, $request, $files)
    {
        return $this->setupRequest($url, 'POST', $request, $files);
    }

}

<?php

namespace Wolfe\Tests\Handler;

use Psr\Http\Message\ResponseInterface;
use Slim\Http\UploadedFile;
use Wolfe\Tests\AbstractFunctionalTest;

class HomeHandlerTest extends AbstractFunctionalTest
{
    public function testGetIndex()
    {
        /** @var ResponseInterface $response */
        $response = $this->get('/');

        $this->assertEquals(200, $response->getStatusCode());
    }

    /**
     * @dataProvider testFileUploads
     * @param $actual
     * @param $expected
     */
    public function testPostIndex($expected, $actual)
    {
        $files = ['csvFileToProcess' => $expected];

        /** @var ResponseInterface $response */
        $response = $this->post('/', null, $files);

        $this->assertEquals(200, $response->getStatusCode());
    }

    public function testFileUploads()
    {
        return array(
            array(
                new UploadedFile(
                    __DIR__ . DIRECTORY_SEPARATOR . '../Resources/GenericExport.csv',
                    'GenericExport.csv',
                    'text/csv',
                    4256,
                    UPLOAD_ERR_OK,
                    true
                ),
                [TRUE, FALSE]
            )
        );
    }
}

//Code that does the work
//index.php
$this->app->post('/', function(ServerRequestInterface $request, ResponseInterface $response) {

    $handler = new HomeHandler($request, $response);

    return $handler->csvPostHandler();

});

<?php


namespace Wolfe\Converter\Handler;


use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Wolfe\Converter\Library\CSVFileChecker;
use Wolfe\Converter\Library\CSVHandler;
use DateTime;

class HomeHandler
{
    /** @var ServerRequestInterface $_request */
    private $_request;

    /** @var ResponseInterface $_response */
    private $_response;

    /**
     * @param ServerRequestInterface $request
     * @param ResponseInterface $response
     */
    public function __construct(ServerRequestInterface $request, ResponseInterface $response)
    {
        $this->_request = $request;
        $this->_response = $response;
    }

    public function csvPostHandler()
    {
        $csvFileChecker = new CSVFileChecker($this->_request);

        if ($csvFileChecker->isValid()) {
            $file = $csvFileChecker->getFile();

            $csvHandler = new CSVHandler($file);
            $writer = $csvHandler->processCSV();

            $date = new DateTime('now');
            $csvFileName = 'CSVOutput' . $date->format('Y-m-d-H-i') . '.csv';
            return $writer->output($csvFileName);
        }

        return null;
    }
}