Adding missing getTransactionId to amazon purchase item

src/Amazon/PurchaseItem.php

@@ -28,6 +28,13 @@ class PurchaseItem
    */
   protected $_product_id;
 
+  /**
+   * transaction_id
+   *
+   * @var string
+   */
+  protected $_transaction_id;
+
   /**
    * purchase_date
    *
@@ -66,6 +73,14 @@ public function getProductId()
     return $this->_product_id;
   }
 
+  /**
+   * @return string
+   */
+  public function getTransactionId()
+  {
+    return $this->_transaction_id;
+  }
+
   /**
    * @return Carbon
    */

tests/Amazon/ResponseTest.php

@@ -0,0 +1,41 @@
+<?php
+use ReceiptValidator\Amazon\Response;
+
+/**
+ * @group library
+ */
+class AmazonResponseTest extends PHPUnit_Framework_TestCase
+{
+
+  public function testInvalidOptionsToConstructor()
+  {
+    $this->setExpectedException("ReceiptValidator\\RuntimeException", "Response must be a scalar value");
+
+    new Response(Response::RESULT_OK, 'invalid');
+  }
+
+  public function testInvalidReceipt()
+  {
+    $response = new Response(Response::RESULT_INTERNAL_ERROR, array(''));
+
+    $this->assertFalse($response->isValid(), 'receipt must be invalid');
+  }
+
+   public function testValidReceipt()
+   {
+     $receipt = json_decode('{"betaProduct":false,"cancelDate":null,"parentProductId":null,"productId":"pack_100","productType":"CONSUMABLE","purchaseDate":1485359133060,"quantity":1,"receiptId":"M3qQCAiytxUzm3G05OworddJDiSi6ijXQGRFSK#AD=:1:11","renewalDate":null,"term":null,"termSku":null,"testTransaction":false}', true);
+
+     $response = new Response(Response::RESULT_OK, $receipt);
+
+     $this->assertTrue($response->isValid(), 'receipt must be valid');
+     $this->assertEquals(Response::RESULT_OK, $response->getResultCode(), 'receipt result code must match');
+
+     $this->assertCount(1, $response->getPurchases(), 'receipt must have single purchase');
+
+     $purchase = $response->getPurchases()[0];
+     $this->assertEquals('pack_100', $purchase->getProductId(), 'productId does not match');
+     $this->assertEquals('M3qQCAiytxUzm3G05OworddJDiSi6ijXQGRFSK#AD=:1:11', $purchase->getTransactionId(), 'transactionId does not match');
+     $this->assertEquals(1, $purchase->getQuantity(), 'quantity does not match');
+   }
+
+}