Added feature to create third party access tokens

lib/PayPal/Auth/OAuthTokenCredential.php

@@ -75,17 +75,26 @@ class OAuthTokenCredential extends PayPalResourceModel
      */
     private $cipher;
 
+    /**
+     * The encryted account number of the merchant on whose behalf the transaction is being done
+     *
+     * @var Subject
+     */
+    private $subject;
+
     /**
      * Construct
      *
      * @param string $clientId     client id obtained from the developer portal
      * @param string $clientSecret client secret obtained from the developer portal
+     * @param null|string $subject      subject used to create Third Party Token
      */
-    public function __construct($clientId, $clientSecret)
+    public function __construct($clientId, $clientSecret, $subject = null)
     {
         $this->clientId = $clientId;
         $this->clientSecret = $clientSecret;
         $this->cipher = new Cipher($this->clientSecret);
+        $this->subject = $subject;
     }
 
     /**
@@ -108,6 +117,16 @@ public function getClientSecret()
         return $this->clientSecret;
     }
 
+    /**
+     * Get the subject used to create Third Party Access Token
+     *
+     * @return string
+     */
+    public function getSubject()
+    {
+        return $this->subject;
+    }
+
     /**
      * Get AccessToken
      *
@@ -267,6 +286,11 @@ private function generateAccessToken($config, $refreshToken = null)
             $params['grant_type'] = 'refresh_token';
             $params['refresh_token'] = $refreshToken;
         }
+
+        if ($this->subject != null && $refreshToken != null) {
+            $params['target_subject'] = $this->subject;
+        }
+
         $payload = http_build_query($params);
         $response = $this->getToken($config, $this->clientId, $this->clientSecret, $payload);
 

tests/PayPal/Test/Auth/OAuthTokenCredentialTest.php

@@ -60,6 +60,27 @@ public function testGetAccessTokenUnit()
         $this->assertNotNull($result);
     }
 
+    public function testGetAccessTokenWithSubjectUnit()
+    {
+        $config = array(
+            'mode' => 'sandbox',
+            'cache.enabled' => true,
+            'cache.FileName' => AuthorizationCacheTest::CACHE_FILE
+        );
+        $cred = new OAuthTokenCredential('clientId', 'clientSecret', 'subject');
+
+        //{"clientId":{"clientId":"clientId","accessToken":"accessToken","tokenCreateTime":1421204091,"tokenExpiresIn":288000000}}
+        AuthorizationCache::push($config, 'clientId', $cred->encrypt('accessTokenWithSubject'), 1421204091, 288000000);
+
+        $apiContext = new ApiContext($cred);
+        $apiContext->setConfig($config);
+        $this->assertEquals('clientId', $cred->getClientId());
+        $this->assertEquals('clientSecret', $cred->getClientSecret());
+        $this->assertEquals('subject', $cred->getSubject());
+        $result = $cred->getAccessToken($config);
+        $this->assertNotNull($result);
+    }
+
     public function testGetAccessTokenUnitMock()
     {
         $config = array(