Fixes #5 : Handle Response::sendHeaders() to not silently returns whe…

…n header already sent

Signed-off-by: Abdul Malik Ikhsan <samsonasik@gmail.com>

src/PhpEnvironment/Response.php

@@ -8,6 +8,7 @@
 
 namespace Laminas\Http\PhpEnvironment;
 
+use Laminas\Http\Exception\RuntimeException;
 use Laminas\Http\Header\MultipleHeaderInterface;
 use Laminas\Http\Response as HttpResponse;
 
@@ -82,7 +83,7 @@ public function contentSent()
     public function sendHeaders()
     {
         if ($this->headersSent()) {
-            return $this;
+            throw new RuntimeException('Cannot send headers, headers already sent');
         }
 
         $status  = $this->renderStatusLine();

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 +101,27 @@ 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());
+    }
+
+    /**
+     * @runInSeparateProcesses
+     */
+    public function testSendHeadersHeadersAlreadySent()
+    {
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('Cannot send headers, headers already sent');
+
+        echo 'test';
+
+        $response = new Response();
+        $response->sendHeaders();
+    }
 }