Ignore empty writes to not mess up chunked transfer encoding

src/Response.php

@@ -96,15 +96,19 @@ public function write($data)
             throw new \Exception('Response head has not yet been written.');
         }
 
+        // prefix with chunk length for chunked transfer encoding
         if ($this->chunkedEncoding) {
             $len = strlen($data);
-            $chunk = dechex($len)."\r\n".$data."\r\n";
-            $flushed = $this->conn->write($chunk);
-        } else {
-            $flushed = $this->conn->write($data);
+
+            // skip empty chunks
+            if ($len === 0) {
+                return true;
+            }
+
+            $data = dechex($len) . "\r\n" . $data . "\r\n";
         }
 
-        return $flushed;
+        return $this->conn->write($data);
     }
 
     public function end($data = null)

tests/ResponseTest.php

@@ -77,6 +77,33 @@ public function testResponseBodyShouldBeChunkedCorrectly()
         $response->end();
     }
 
+    public function testResponseBodyShouldSkipEmptyChunks()
+    {
+        $conn = $this
+            ->getMockBuilder('React\Socket\ConnectionInterface')
+            ->getMock();
+        $conn
+            ->expects($this->at(4))
+            ->method('write')
+            ->with("5\r\nHello\r\n");
+        $conn
+            ->expects($this->at(5))
+            ->method('write')
+            ->with("5\r\nWorld\r\n");
+        $conn
+            ->expects($this->at(6))
+            ->method('write')
+            ->with("0\r\n\r\n");
+
+        $response = new Response($conn);
+        $response->writeHead();
+
+        $response->write('Hello');
+        $response->write('');
+        $response->write('World');
+        $response->end();
+    }
+
     public function testResponseShouldEmitEndOnStreamEnd()
     {
         $ended = false;