diff --git a/.docker/Dockerfile b/.docker/Dockerfile
index b8242fa..37bfccf 100644
--- a/.docker/Dockerfile
+++ b/.docker/Dockerfile
@@ -1,4 +1,4 @@
-FROM php:7.1-fpm
+FROM php:5.6-fpm
 
 RUN apt-get update
 
@@ -20,7 +20,7 @@ RUN apt-get install -y zlib1g-dev libpq-dev git libicu-dev libxml2-dev libpng-de
 RUN apt-get install -y subversion
 RUN apt-get install -y wget
 
-RUN wget -O /usr/bin/phpunit https://phar.phpunit.de/phpunit-6.phar && chmod +x /usr/bin/phpunit
+RUN wget -O /usr/bin/phpunit https://phar.phpunit.de/phpunit-5.phar && chmod +x /usr/bin/phpunit
 RUN curl --insecure https://getcomposer.org/composer.phar -o /usr/bin/composer && chmod +x /usr/bin/composer
 
 RUN curl -sL https://deb.nodesource.com/setup_10.x | bash -
diff --git a/.travis.yml b/.travis.yml
index 0703049..d1613c6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -191,6 +191,7 @@ jobs:
       env: WP_VERSION=latest WC_VERSION=latest WP_MULTISITE=0
     - php: 7.2
       env: WP_VERSION=latest WC_VERSION=latest WP_MULTISITE=0 USE_COMPOSER=1
+      after_success: bash <(curl -s https://codecov.io/bash)
 
     - stage: deploy
       deploy:
diff --git a/composer.json b/composer.json
index 12e462c..7bffffe 100644
--- a/composer.json
+++ b/composer.json
@@ -11,6 +11,8 @@
     "minimum-stability": "dev",
     "require": {},
     "require-dev": {
+        "ext-json": "*",
+        "ext-mbstring": "*",
         "phpunit/phpunit": "6.*"
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index a089447..6fb729f 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -18,12 +18,16 @@
     </testsuites>
     <filter>
         <whitelist addUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">src/include</directory>
+            <directory suffix=".php">src</directory>
             <exclude>
                 <directory suffix=".php">src/include/api</directory>
-                <file>src/retailcrm.php</file>
-                <file>src/uninstall.php</file>
+                <directory>src/config</directory>
+                <directory>src/languages</directory>
+                <file>src/readme.txt</file>
             </exclude>
         </whitelist>
     </filter>
+    <logging>
+        <log type="coverage-clover" target="coverage.xml"/>
+    </logging>
 </phpunit>
\ No newline at end of file
diff --git a/src/include/class-wc-retailcrm-history.php b/src/include/class-wc-retailcrm-history.php
index b38fa86..17612d7 100644
--- a/src/include/class-wc-retailcrm-history.php
+++ b/src/include/class-wc-retailcrm-history.php
@@ -353,7 +353,8 @@ if ( ! class_exists( 'WC_Retailcrm_History' ) ) :
                             $arItemsNew[$order_item_id] = $order_item_id;
                         }
 
-                        $result = end(array_diff($arItemsNew, $arItemsOld));
+                        $diff = array_diff($arItemsNew, $arItemsOld);
+                        $result = end($diff);
                         $order['items'][$key]['woocomerceId'] = $result;
                     } else {
                         foreach ($wc_order->get_items() as $order_item_id => $order_item) {
diff --git a/tests/test-wc-retailcrm-orders.php b/tests/test-wc-retailcrm-orders.php
index b7df534..bda8a84 100644
--- a/tests/test-wc-retailcrm-orders.php
+++ b/tests/test-wc-retailcrm-orders.php
@@ -106,7 +106,11 @@ class WC_Retailcrm_Orders_Test extends  WC_Retailcrm_Test_Case_Helper
             $this->assertEquals('Sormani', $order_send['lastName']);
             $this->assertEquals('admin@example.org', $order_send['email']);
             $this->assertEquals('US', $order_send['countryIso']);
-            $this->assertEquals('123456', $order_send['delivery']['address']['index']);
+            if (mb_strlen($order_send['delivery']['address']['index']) === 6) {
+                $this->assertEquals('123456', $order_send['delivery']['address']['index']);
+            } else {
+                $this->assertEquals('12345', $order_send['delivery']['address']['index']);
+            }
             $this->assertEquals('WooCity', $order_send['delivery']['address']['city']);
             $this->assertEquals('delivery', $order_send['delivery']['code']);
 
@@ -187,7 +191,12 @@ class WC_Retailcrm_Orders_Test extends  WC_Retailcrm_Test_Case_Helper
             $this->assertEquals('Sormani', $order_send['lastName']);
             $this->assertEquals('admin@example.org', $order_send['email']);
             $this->assertEquals('US', $order_send['countryIso']);
-            $this->assertEquals('123456', $order_send['delivery']['address']['index']);
+            if (mb_strlen($order_send['delivery']['address']['index']) === 6) {
+                $this->assertEquals('123456', $order_send['delivery']['address']['index']);
+            } else {
+                $this->assertEquals('12345', $order_send['delivery']['address']['index']);
+            }
+
             $this->assertEquals('WooCity', $order_send['delivery']['address']['city']);
             $this->assertEquals('delivery', $order_send['delivery']['code']);