added browser property headers to be able to change the headers with …

…the methods withHeader and withoutHeader

src/Browser.php

@@ -23,6 +23,7 @@ class Browser
     private $transaction;
     private $baseUrl;
     private $protocolVersion = '1.1';
+    private $headers = array();
 
     /**
      * The `Browser` is responsible for sending HTTP requests to your HTTP server
@@ -725,6 +726,32 @@ public function withResponseBuffer($maximumSize)
         ));
     }
 
+    /**
+     * @param $header
+     * @param $value
+     * @return Browser
+     *@todo documentation
+     *
+     */
+    public function withHeader($header, $value)
+    {
+        $browser = clone $this;
+        $browser->headers[$header] = $value;
+
+        return $browser;
+    }
+
+    public function withoutHeader($header)
+    {
+        $browser = clone $this;
+
+        if (array_key_exists($header, $browser->headers)) {
+            unset($browser->headers[$header]);
+        }
+
+        return $browser;
+    }
+
     /**
      * Changes the [options](#options) to use:
      *
@@ -784,7 +811,12 @@ private function requestMayBeStreaming($method, $url, array $headers = array(),
         }
 
         return $this->transaction->send(
-            new Request($method, $url, $headers, $body, $this->protocolVersion)
+            new Request($method, $url, $this->mergeHeaders($headers), $body, $this->protocolVersion)
         );
     }
+
+    private function mergeHeaders(array $headers)
+    {
+        return array_merge($headers, $this->headers);
+    }
 }

tests/BrowserTest.php

@@ -503,4 +503,17 @@ public function testCancelGetRequestShouldCancelUnderlyingSocketConnection()
         $promise = $this->browser->get('http://example.com/');
         $promise->cancel();
     }
+
+    public function testWithElseHeader()
+    {
+        $this->browser = $this->browser->withHeader('User-Agent', 'ACMC');
+
+        $that = $this;
+        $this->sender->expects($this->once())->method('send')->with($this->callback(function (RequestInterface $request) use ($that) {
+            $that->assertEquals('ACMC', $request->getHeader('User-Agent'));
+            return true;
+        }))->willReturn(new Promise(function () { }));
+
+        $this->browser->get('http://example.com/');
+    }
 }