Fix Http client headers when array data is used.

When building a client request with constructor arguments, the headers
should be applied before the body is set. This is necessary as setting
the body can change the content-type based on the contents. Arrays are
converted into urlencoded data, which needs to override the
content-type on the request.

src/Http/Client/Request.php

@@ -45,12 +45,12 @@ public function __construct($url = '', $method = self::METHOD_GET, array $header
         $this->validateMethod($method);
         $this->method = $method;
         $this->uri = $this->createUri($url);
-        $this->body($data);
         $headers += [
             'Connection' => 'close',
             'User-Agent' => 'CakePHP'
         ];
         $this->addHeaders($headers);
+        $this->body($data);
     }
 
     /**

tests/TestCase/Network/Http/RequestTest.php

@@ -22,6 +22,45 @@
  */
 class RequestTest extends TestCase
 {
+    /**
+     * test string ata, header and constructor
+     *
+     * @return void
+     */
+    public function testConstructorStringData()
+    {
+        $headers = [
+            'Content-Type' => 'application/json',
+            'Authorization' => 'Bearer valid-token',
+        ];
+        $data = ['a' => 'b', 'c' => 'd'];
+        $request = new Request('http://example.com', 'POST', $headers, json_encode($data));
+
+        $this->assertEquals('http://example.com', $request->url());
+        $this->assertEquals('POST', $request->getMethod());
+        $this->assertEquals('application/json', $request->getHeaderLine('Content-Type'));
+        $this->assertEquals(json_encode($data), $request->body());
+    }
+
+    /**
+     * test array data, header and constructor
+     *
+     * @return void
+     */
+    public function testConstructorArrayData()
+    {
+        $headers = [
+            'Content-Type' => 'application/json',
+            'Authorization' => 'Bearer valid-token',
+        ];
+        $data = ['a' => 'b', 'c' => 'd'];
+        $request = new Request('http://example.com', 'POST', $headers, $data);
+
+        $this->assertEquals('http://example.com', $request->url());
+        $this->assertEquals('POST', $request->getMethod());
+        $this->assertEquals('application/x-www-form-urlencoded', $request->getHeaderLine('Content-Type'));
+        $this->assertEquals('a=b&c=d', $request->body());
+    }
 
     /**
      * test url method