Fixes #5 : Handle Response::sendHeaders() to not silently returns when header already sent

docs/book/response.md

@@ -138,3 +138,16 @@ $response->setContent(<<<EOS
 </html>
 EOS);
 ```
+
+### handle Headers already sent
+
+Since 2.13.0, we can handle header already sent by pass callable via `Response::setHeadersSentHandler()`:
+
+```php
+use Laminas\Http\Response;
+
+$response = new Response();
+$response->setHeadersSentHandler(function ($response): void {
+    throw new RuntimeException('Cannot send headers, headers already sent');
+});
+```

src/PhpEnvironment/Response.php

@@ -8,6 +8,7 @@
 
 namespace Laminas\Http\PhpEnvironment;
 
+use Laminas\Http\Exception\InvalidArgumentException;
 use Laminas\Http\Header\MultipleHeaderInterface;
 use Laminas\Http\Response as HttpResponse;
 
@@ -29,6 +30,11 @@ class Response extends HttpResponse
      */
     protected $contentSent = false;
 
+    /**
+     * @var null|callable
+     */
+    private $headersSentHandler;
+
     /**
      * Return the HTTP version for this response
      *
@@ -74,6 +80,14 @@ public function contentSent()
         return $this->contentSent;
     }
 
+    /**
+     * @return void
+     */
+    public function setHeadersSentHandler(callable $handler)
+    {
+        $this->headersSentHandler = $handler;
+    }
+
     /**
      * Send HTTP headers
      *
@@ -82,6 +96,10 @@ public function contentSent()
     public function sendHeaders()
     {
         if ($this->headersSent()) {
+            if ($this->headersSentHandler) {
+                call_user_func($this->headersSentHandler, $this);
+            }
+
             return $this;
         }
 

test/PhpEnvironment/ResponseTest.php

@@ -9,6 +9,7 @@
 namespace LaminasTest\Http\PhpEnvironment;
 
 use Laminas\Http\Exception\InvalidArgumentException;
+use Laminas\Http\Exception\RuntimeException;
 use Laminas\Http\PhpEnvironment\Response;
 use PHPUnit\Framework\TestCase;
 
@@ -100,4 +101,26 @@ public function testCanExplicitlySetVersion()
         $this->expectException(InvalidArgumentException::class);
         $response->setVersion('laminas/2.0');
     }
+
+    /**
+     * @runInSeparateProcess
+     */
+    public function testSendHeadersHeadersNotAlreadySent()
+    {
+        $response = new Response();
+        $this->assertInstanceOf(Response::class, $response->sendHeaders());
+    }
+
+    public function testSendHeadersHeadersAlreadySentPassValidHandler()
+    {
+        $response = new Response();
+        $response->setHeadersSentHandler(function ($response) {
+            throw new RuntimeException('Cannot send headers, headers already sent');
+        });
+
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('Cannot send headers, headers already sent');
+
+        $response->sendHeaders();
+    }
 }