Refactor to be able to use stream or filename for response body

This is following on from what mwop suggested in that the body of the
response can be set from either a string or a file. It's making use of a
Stream object and the body is instantiated similarly to XmlResponse as
how that works makes a lot of sense in this case.

Author: settermjd

src/Response/DownloadResponse.php

@@ -9,6 +9,7 @@
 
 namespace Zend\Diactoros\Response;
 
+use Psr\Http\Message\StreamInterface;
 use Zend\Diactoros\Exception\InvalidArgumentException;
 use Zend\Diactoros\Response;
 
@@ -41,20 +42,20 @@ class DownloadResponse extends Response
 
     /**
      * DownloadResponse constructor.
-     * @param $body
-     * @param int $status
-     * @param string $filename
+     * @param string|StreamInterface $body String or stream for the message body.
+     * @param int $status Integer status code for the response; 200 by default.
+     * @param string $filename The name of the file to be downloaded
+     * @param array $headers Array of headers to use at initialization.
+     * @throws InvalidArgumentException if $text is neither a string or stream.
      * @param array $headers
      */
-    public function __construct($body, int $status = 200, string $filename = '', array $headers = [])
+    public function __construct($body, int $status = 200, string $filename = 'download', array $headers = [])
     {
-        $content = new Stream('php://temp', 'wb+');
-        $content->write($body);
-        $content->rewind();
-
-        $headers = $this->prepareDownloadHeaders($filename, $headers);
-
-        parent::__construct($content, $status, $headers);
+        parent::__construct(
+            $this->createBody($body),
+            $status,
+            $this->prepareDownloadHeaders($filename, $headers)
+        );
     }
 
     /**
@@ -66,13 +67,13 @@ public function __construct($body, int $status = 200, string $filename = '', arr
     private function getDownloadHeaders(string $filename): array
     {
         $headers = [];
-        $headers['cache-control'] = ['must-revalidate'];
-        $headers['content-description'] = ['File Transfer'];
-        $headers['content-disposition'] = [sprintf('attachment; filename=%s', $filename)];
-        $headers['content-transfer-encoding'] = ['Binary'];
-        $headers['content-type'] = ['text/csv; charset=utf-8'];
-        $headers['expires'] = ['0'];
-        $headers['pragma'] = ['Public'];
+        $headers['cache-control'] = 'must-revalidate';
+        $headers['content-description'] = 'File Transfer';
+        $headers['content-disposition'] = sprintf('attachment; filename=%s', $filename);
+        $headers['content-transfer-encoding'] = 'Binary';
+        $headers['content-type'] = 'application/octet-stream';
+        $headers['expires'] = '0';
+        $headers['pragma'] = 'Public';
 
         return $headers;
     }
@@ -120,4 +121,29 @@ private function prepareDownloadHeaders(string $filename, array $headers = []) :
 
         return array_merge($headers, $this->getDownloadHeaders($filename));
     }
+
+    /**
+     * @param string|StreamInterface $content
+     * @return StreamInterface
+     * @throws InvalidArgumentException if $body is neither a string nor a stream
+     */
+    private function createBody($content): StreamInterface
+    {
+        if ($content instanceof StreamInterface) {
+            return $content;
+        }
+
+        if (!is_string($content)) {
+            throw new InvalidArgumentException(sprintf(
+                'Invalid content (%s) provided to %s',
+                (is_object($content) ? get_class($content) : gettype($content)),
+                __CLASS__
+            ));
+        }
+
+        $body = new Stream('php://temp', 'wb+');
+        $body->write($content);
+        $body->rewind();
+        return $body;
+    }
 }

test/Response/DownloadResponseTest.php

@@ -13,6 +13,7 @@
 use PHPUnit\Framework\TestCase;
 use Zend\Diactoros\Response;
 use Zend\Diactoros\Response\DownloadResponse;
+use Zend\Diactoros\Stream;
 
 class DownloadResponseTest extends TestCase
 {
@@ -47,10 +48,59 @@ public function setUp()
 
     public function testCanCreateResponseFromString()
     {
-        $csvString = file_get_contents($this->root->url() . '/files/valid.csv');
-        $response = new DownloadResponse($csvString);
+        $body = file_get_contents($this->root->url() . '/files/valid.csv');
+        $response = new DownloadResponse($body);
         $this->assertInstanceOf(Response::class, $response);
-        $this->assertEquals($csvString, (string) $response->getBody()->getContents());
-        $this->assertArrayHasKey('cache-control', $response->getHeaders());
+        $this->assertEquals($body, (string) $response->getBody());
+        $this->assertEquals(619, $response->getBody()->getSize());
+        $this->assertHasValidResponseHeaders($response);
+        $this->assertSame('attachment; filename=download', $response->getHeaderLine('content-disposition'));
+    }
+
+    public function testCanCreateResponseFromFilename()
+    {
+        $body = new Stream($this->root->url() . '/files/valid.csv');
+        $response = new DownloadResponse($body);
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertEquals(
+            file_get_contents($this->root->url() . '/files/valid.csv'),
+            (string) $response->getBody()
+        );
+        $this->assertHasValidResponseHeaders($response);
+        $this->assertSame('attachment; filename=download', $response->getHeaderLine('content-disposition'));
+    }
+
+    public function testCanSendResponseWithCustomFilename()
+    {
+        $body = new Stream($this->root->url() . '/files/valid.csv');
+        $response = new DownloadResponse($body, 200, 'valid.csv');
+        $this->assertInstanceOf(Response::class, $response);
+        $this->assertEquals(
+            file_get_contents($this->root->url() . '/files/valid.csv'),
+            (string) $response->getBody()
+        );
+        $this->assertHasValidResponseHeaders($response, 'valid.csv');
+        $this->assertSame('attachment; filename=valid.csv', $response->getHeaderLine('content-disposition'));
+    }
+
+    /**
+     * @param DownloadResponse $response
+     * @param string $filename
+     */
+    private function assertHasValidResponseHeaders(DownloadResponse $response, $filename = 'download'): void
+    {
+        $requiredHeaders = [
+            'cache-control' => 'must-revalidate',
+            'content-description' => 'File Transfer',
+            'content-disposition' => sprintf('attachment; filename=%s', $filename),
+            'content-transfer-encoding' => 'Binary',
+            'content-type' => 'application/octet-stream',
+            'expires' => '0',
+            'pragma' => 'Public'
+        ];
+        foreach ($requiredHeaders as $header => $value) {
+            $this->assertTrue($response->hasHeader($header));
+            $this->assertSame($value, $response->getHeaderLine($header));
+        }
     }
 }