diff --git a/.gitignore b/.gitignore
index c37da9f..47e1659 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 /.idea
 /vendor
-composer.lock
\ No newline at end of file
+composer.lock
+.phpunit.result.cache
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..9e19205
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,10 @@
+language: php
+
+php:
+    - 7.1
+    - 7.2
+    - 7.3
+
+before_install:
+    - composer selfupdate
+    - composer install --dev --no-interaction --prefer-dist
diff --git a/composer.json b/composer.json
index f232e70..b200d9a 100644
--- a/composer.json
+++ b/composer.json
@@ -13,19 +13,26 @@
         "php": ">=7.1",
         "ext-curl": "*",
         "ext-json": "*",
-        "guzzle/guzzle": "~3.7",
+        "guzzlehttp/guzzle": "~6.3",
         "jms/serializer": "~0.12 || ~1.4.2",
         "symfony/validator": "~2.8|~3.4|~4.0",
         "doctrine/cache": "~1.6",
         "psr/log": "~1.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~7"
+        "phpunit/phpunit": "~8.0"
     },
     "support": {
         "email": "support@retailcrm.ru"
     },
     "autoload": {
-        "psr-0": { "AtolOnlineClient\\": "src/" }
+        "psr-0": {
+            "AtolOnlineClient\\": "src/"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "AtolOnlineClient\\": "tests/"
+        }
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index ff40e8a..dfb6b9b 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,24 +1,27 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<!-- http://www.phpunit.de/manual/current/en/appendixes.configuration.html -->
-<phpunit
-    backupGlobals               = "false"
-    backupStaticAttributes      = "false"
-    colors                      = "true"
-    convertErrorsToExceptions   = "true"
-    convertNoticesToExceptions  = "true"
-    convertWarningsToExceptions = "true"
-    processIsolation            = "true"
-    stopOnFailure               = "false"
-    syntaxCheck                 = "false"
-    bootstrap                   = "bootstrap.php" >
+<phpunit bootstrap="tests/bootstrap.php"
+         backupGlobals="false"
+         backupStaticAttributes="false"
+         colors="true"
+         verbose="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         processIsolation="false"
+         stopOnFailure="false">
 
     <testsuites>
 
         <testsuite name="php">
-            <directory>./tests/*/Tests</directory>
+            <directory>./tests/AtolOnlineClient</directory>
         </testsuite>
 
     </testsuites>
 
+    <filter>
+        <whitelist>
+            <directory>src</directory>
+        </whitelist>
+    </filter>
 </phpunit>
diff --git a/src/AtolOnlineClient/AtolOnline.php b/src/AtolOnlineClient/AtolOnline.php
index cc2d642..1191f29 100644
--- a/src/AtolOnlineClient/AtolOnline.php
+++ b/src/AtolOnlineClient/AtolOnline.php
@@ -3,18 +3,25 @@
 namespace AtolOnlineClient;
 
 use AtolOnlineClient\Configuration\Connection;
+use AtolOnlineClient\Exception\InvalidResponseException;
 use AtolOnlineClient\Response\OperationResponse;
-use Guzzle\Http\Client;
+use GuzzleHttp\Client;
 use JMS\Serializer\DeserializationContext;
+use JMS\Serializer\Exception\RuntimeException;
 use JMS\Serializer\SerializationContext;
 use JMS\Serializer\SerializerBuilder;
+use JMS\Serializer\SerializerInterface;
 
 class AtolOnline
 {
-
+    /**
+     * @var SerializerInterface
+     */
     private $serializer;
 
-    /** @var AtolOnlineApi */
+    /**
+     * @var AtolOnlineApi
+     */
     private $api;
 
     public function __construct()
@@ -22,37 +29,48 @@ class AtolOnline
         $this->serializer = SerializerBuilder::create()->build();
     }
 
-    public function createConfiguration()
+    /**
+     * @return Configuration
+     */
+    public function createConfiguration(): ConfigurationInterface
     {
         return new Configuration();
     }
 
     /**
-     * @param $response
+     * @param string $response
      * @return OperationResponse
      */
-    public function deserializeOperationResponse($response)
+    public function deserializeOperationResponse(string $response): OperationResponse
     {
-        return $this->serializer->deserialize(
-            $response,
-            OperationResponse::class,
-            'json',
-            DeserializationContext::create()->setGroups(['post'])
-        );
+        try {
+            return $this->serializer->deserialize(
+                $response,
+                OperationResponse::class,
+                'json',
+                DeserializationContext::create()->setGroups(['post'])
+            );
+        } catch (RuntimeException $exception) {
+            throw $this->createInvalidResponseException($response, $exception);
+        }
     }
 
     /**
      * @param $response
      * @return OperationResponse
      */
-    public function deserializeCheckStatusResponse($response)
+    public function deserializeCheckStatusResponse($response): OperationResponse
     {
-        return $this->serializer->deserialize(
-            $response,
-            OperationResponse::class,
-            'json',
-            DeserializationContext::create()->setGroups(['get'])
-        );
+        try {
+            return $this->serializer->deserialize(
+                $response,
+                OperationResponse::class,
+                'json',
+                DeserializationContext::create()->setGroups(['get'])
+            );
+        } catch (RuntimeException $exception) {
+            throw $this->createInvalidResponseException($response, $exception);
+        }
     }
 
     /**
@@ -69,11 +87,11 @@ class AtolOnline
     }
 
     /**
-     * @param $client
+     * @param Client $client
      * @param Connection $connection
      * @return AtolOnlineApi
      */
-    public function createApi(Client $client, Connection $connection)
+    public function createApi(Client $client, Connection $connection): AtolOnlineApi
     {
         if (!$this->api) {
             $this->api = new AtolOnlineApi($client, $connection);
@@ -85,8 +103,30 @@ class AtolOnline
     /**
      * @return AtolOnlineApi
      */
-    public function getApi()
+    public function getApi(): AtolOnlineApi
     {
         return $this->api;
     }
-}
\ No newline at end of file
+
+    /**
+     * @param string $response
+     * @param RuntimeException $previous
+     * @return InvalidResponseException
+     */
+    private function createInvalidResponseException(string $response, RuntimeException $previous): InvalidResponseException
+    {
+        $exception = new InvalidResponseException($previous->getMessage());
+
+        preg_match('/<head><title>(\d+) ([\w ]+)<\/title><\/head>/m', $response, $matches);
+
+        if (count($matches) === 3) {
+            [, $code, $message] = $matches;
+
+            $exception
+                ->setCodeError($code)
+                ->setMessageError($message);
+        }
+
+        return $exception;
+    }
+}
diff --git a/src/AtolOnlineClient/AtolOnlineApi.php b/src/AtolOnlineClient/AtolOnlineApi.php
index 1968852..10c2325 100644
--- a/src/AtolOnlineClient/AtolOnlineApi.php
+++ b/src/AtolOnlineClient/AtolOnlineApi.php
@@ -4,36 +4,29 @@ namespace AtolOnlineClient;
 
 use AtolOnlineClient\Configuration\Connection;
 use Doctrine\Common\Cache\Cache;
-
-use Guzzle\Http\Client;
-
-use Guzzle\Http\Exception\BadResponseException;
-use Guzzle\Http\Message\Response;
+use GuzzleHttp\Client;
+use GuzzleHttp\Exception\BadResponseException;
+use Psr\Http\Message\ResponseInterface;
 use Psr\Log\LoggerInterface;
 
 class AtolOnlineApi
 {
+    public const API_VERSION_V4 = 'v4';
+    public const API_VERSION_V3 = 'v3';
 
-    const API_VERSION_V4 = 'v4';
-    const API_VERSION_V3 = 'v3';
-
-    const TOKEN_CACHE_KEY = 'crm_fiscal_atol_online_token';
-    const TOKEN_CACHE_TIME = 60 * 60 * 24;
+    public const TOKEN_CACHE_KEY = 'crm_fiscal_atol_online_token';
+    public const TOKEN_CACHE_TIME = 86400;
 
     private $baseApiUrl = 'https://online.atol.ru/possystem';
-
-    private $login;
-    private $pass;
-    private $groupCode;
-    private $debug;
+    private $testApiUrl = 'https://testonline.atol.ru/possystem';
 
     /**
-     * @var LoggerInterface
+     * @var LoggerInterface|null
      */
     private $logger;
 
     /**
-     * @var Cache
+     * @var Cache|null
      */
     private $cache;
 
@@ -42,6 +35,11 @@ class AtolOnlineApi
      */
     private $client;
 
+    /**
+     * @var Connection
+     */
+    private $connection;
+
     /**
      * @var int
      */
@@ -52,9 +50,6 @@ class AtolOnlineApi
      */
     private $attemptsCheckStatus;
 
-    /** @var string  */
-    private $version;
-
     /**
      * @param Client $client
      * @param Connection $connectionConfig
@@ -62,18 +57,44 @@ class AtolOnlineApi
     public function __construct(Client $client, Connection $connectionConfig)
     {
         $this->client = $client;
-        $this->login = $connectionConfig->login;
-        $this->pass = $connectionConfig->pass;
-        $this->groupCode = $connectionConfig->group;
-        if (!$connectionConfig->version) {
-            $connectionConfig->version = self::API_VERSION_V3;
-        }
-        $this->version = $connectionConfig->version;
-        $this->debug = $connectionConfig->isDebug();
+        $this->connection = $connectionConfig;
+
         $this->attempts = 0;
-        if ($connectionConfig->isTestMode()) {
-            $this->baseApiUrl = 'https://testonline.atol.ru/possystem';
-        }
+    }
+
+    /**
+     * @param LoggerInterface $logger
+     */
+    public function setLogger(LoggerInterface $logger): void
+    {
+        $this->logger = $logger;
+    }
+
+    /**
+     * @param Cache $cache
+     */
+    public function setCache(Cache $cache): void
+    {
+        $this->cache = $cache;
+    }
+
+    /**
+     * @param string $version
+     * @return AtolOnlineApi
+     */
+    public function setVersion(string $version): AtolOnlineApi
+    {
+        $this->connection->version = $version;
+
+        return $this;
+    }
+
+    /**
+     * @return string
+     */
+    public function getVersion(): string
+    {
+        return $this->connection->version ?: self::API_VERSION_V3;
     }
 
     /**
@@ -84,9 +105,7 @@ class AtolOnlineApi
      */
     public function sell($paymentReceiptRequest)
     {
-        if ($response = $this->sendOperationRequest('sell', $paymentReceiptRequest)) {
-            return $response->getBody()->__toString();
-        };
+        return $this->sendOperationRequest('sell', $paymentReceiptRequest);
     }
 
     /**
@@ -97,74 +116,48 @@ class AtolOnlineApi
      */
     public function sellRefund($paymentReceiptRequest)
     {
-        if ($response = $this->sendOperationRequest('sell_refund', $paymentReceiptRequest)) {
-            return $response->getBody()->__toString();
-        };
+        return $this->sendOperationRequest('sell_refund', $paymentReceiptRequest);
     }
 
     /**
      * Запрос для проверки статуса
      *
-     * @param $uuid
+     * @param string $uuid
      * @return mixed
      */
     public function checkStatus($uuid)
     {
         $token = $this->getToken();
+
         $url = $this->buildUrl('report/'.$uuid, $token);
-        $request = $this->client->get($url);
 
         try {
             $this->attemptsCheckStatus++;
-            $response = $request->send();
-        } catch (BadResponseException $e) {
-            $this->cache->delete($this->getTokenCacheKey());
-            $body = json_decode($e->getResponse()->getBody());
-            if ($this->isTokenExpired($body) && $this->attemptsCheckStatus <= 1) {
+            $response = $this->client->get($url);
+        } catch (BadResponseException $exception) {
+            if ($this->cache) {
+                $this->cache->delete($this->getTokenCacheKey());
+            }
+
+            $response = $exception->getResponse();
+            $body = json_decode($response->getBody(), false);
+
+            if ($this->attemptsCheckStatus <= 1 && $this->isTokenExpired($body)) {
                 return $this->checkStatus($uuid);
             }
-            $response = $e->getResponse();
         }
 
-        if ($response) {
-            $this->logDebug($url, $uuid, $response);
+        $this->logDebug($url, $uuid, $response);
 
-            return $response->getBody()->__toString();
-        }
-
-        return false;
-    }
-
-    /**
-     * @param $logger
-     */
-    public function setLogger(LoggerInterface $logger)
-    {
-        $this->logger = $logger;
-    }
-
-    /**
-     * @param Cache $cache
-     */
-    public function setCache(Cache $cache)
-    {
-        $this->cache = $cache;
-    }
-
-    /**
-     * @param mixed $version
-     */
-    public function setVersion($version): void
-    {
-        $this->version = $version;
+        return $response->getBody()->__toString();
     }
 
     /**
      * @return string
      */
-    public function getVersion(): string
+    protected function getUri(): string
     {
-        return $this->version;
+        return $this->connection->isTestMode() ? $this->testApiUrl : $this->baseApiUrl;
     }
 
     /**
@@ -174,134 +167,154 @@ class AtolOnlineApi
     protected function getToken()
     {
         $data = [
-            'login' => $this->login,
-            'pass' => $this->pass,
+            'login' => $this->connection->login,
+            'pass' => $this->connection->pass,
         ];
 
-        if ($token = $this->cache->fetch($this->getTokenCacheKey())) {
+        if ($this->cache && ($token = $this->cache->fetch($this->getTokenCacheKey()))) {
             return $token;
         }
 
         $dataJson = json_encode((object)$data, JSON_UNESCAPED_UNICODE);
-        $url = $this->baseApiUrl
-            .'/'.$this->version
-            .'/getToken';
 
-        $request = $this->client->createRequest('POST', $url, null, $dataJson);
+        $url = $this->getUri().'/'.$this->connection->version.'/getToken';
+
         $response = false;
         try {
-            $response = $this->client->send($request);
-        } catch (BadResponseException $e) {
-            if ($this->logger) {
-                $this->logger->error($e->getResponse()->getBody());
+            $response = $this->client->post($url, ['body' => $dataJson]);
+        } catch (BadResponseException $exception) {
+            if ($this->logger && $exception->getResponse()) {
+                $this->logger->error((string) $exception->getResponse()->getBody());
             }
         }
 
         if ($response) {
-            $response = json_decode($response->getBody());
+            $response = json_decode($response->getBody(), true);
 
-            if ($this->version === self::API_VERSION_V4) {
-                if (!isset ($response->error)) {
-                    $this->cache->save($this->getTokenCacheKey(), $response->token, self::TOKEN_CACHE_TIME);
-
-                    return $response->token;
-                } else {
-                    $this->logger->error($response->error->code . ' '. $response->error->text);
+            if ($this->connection->isVersion4()) {
+                if ($this->cache && !isset($response['error'])) {
+                    $this->cache->save($this->getTokenCacheKey(), $response['token'], self::TOKEN_CACHE_TIME);
                 }
-            } else {
-                if (isset($response->code) && ($response->code == 1 || $response->code == 0)) {
-                    $this->cache->save($this->getTokenCacheKey(), $response->token, self::TOKEN_CACHE_TIME);
 
-                    return $response->token;
+                if ($this->logger && isset($response['error'])) {
+                    $this->logger->error($response['error']['code'] . ' '. $response['error']['text']);
                 }
+
+                if (!isset($response['error'])) {
+                    return $response['token'];
+                }
+
+               return false;
             }
 
+            if (isset($response['code']) && in_array($response['code'], [0, 1], true)) {
+                if ($this->cache) {
+                    $this->cache->save($this->getTokenCacheKey(), $response['token'], self::TOKEN_CACHE_TIME);
+                }
+
+                return $response['token'];
+            }
         }
 
 
         return false;
     }
 
-    /**
-     * @return string
-     */
-    protected function getTokenCacheKey()
-    {
-        return self::TOKEN_CACHE_KEY.'_'.md5($this->login.$this->pass).'_'.$this->version;
-    }
-
     /**
      * @param string $operation
-     * @param null $token
+     * @param string|null $token
      * @return string
      */
-    protected function buildUrl($operation, $token = null)
+    protected function buildUrl(string $operation, string $token = null): string
     {
-        $url = $this->baseApiUrl
-            .'/'.$this->version
-            .'/'.$this->groupCode
+        $url = $this->getUri()
+            .'/'.$this->connection->version
+            .'/'.$this->connection->group
             .'/'.$operation;
 
-        if ($token) {
-            if ($this->version === self::API_VERSION_V4) {
-                $url .= '?token='.$token;
-            } elseif ($this->version === self::API_VERSION_V3) {
-                $url .= '?tokenid='.$token;
-            }
+        if (!$token) {
+            return $url;
         }
 
-        return $url;
+        if ($this->getVersion() === self::API_VERSION_V4) {
+            return $url.'?token='.$token;
+        }
+
+        return $url.'?tokenid='.$token;
     }
 
     /**
      * @param string $operation
-     * @param string $data
-     * @return Response|bool
+     * @param mixed $data
+     * @return string
      */
-    protected function sendOperationRequest($operation, $data)
+    protected function sendOperationRequest(string $operation, $data): string
     {
         $token = $this->getToken();
+
         $url = $this->buildUrl($operation, $token);
 
-        $request = $this->client->createRequest('POST', $url, null, $data);
         try {
             $this->attempts++;
-            $response = $this->client->send($request);
+            $response = $this->client->post($url, ['body' => $data]);
         } catch (BadResponseException $e) {
-            $this->cache->delete($this->getTokenCacheKey());
-            $body = json_decode($e->getResponse()->getBody());
+            if ($this->cache) {
+                $this->cache->delete($this->getTokenCacheKey());
+            }
+
+            $response = $e->getResponse();
+
+            $body = json_decode($response->getBody()->__toString(), false);
+
             if ($this->isTokenExpired($body) && $this->attempts <= 1) {
                 return $this->sendOperationRequest($operation, $data);
             }
-            $response = $e->getResponse();
         }
 
         if ($response) {
             $this->logDebug($url, $data, $response);
         }
 
-        return $response;
+        return $response->getBody()->__toString();
     }
 
-    protected function logDebug($url, $data, Response $response)
+    /**
+     * @param string $url
+     * @param string $data
+     * @param ResponseInterface $response
+     */
+    protected function logDebug(string $url, string $data, ResponseInterface $response): void
     {
-        if ($this->debug && $this->logger) {
-            $v = "* URL: ".$url;
+        if ($this->logger && $this->connection->isDebug()) {
+            $headers = [];
+
+            foreach ($response->getHeaders() as $key => $value) {
+                $headers[] = implode(': ', [$key, $value[0]]);
+            }
+
+            $v = '* URL: '.$url;
             $v .= "\n * POSTFIELDS: ".$data;
-            $v .= "\n * RESPONSE HEADERS: ".$response->getRawHeaders();
+            $v .= "\n * RESPONSE HEADERS: ".implode(', ', $headers);
             $v .= "\n * RESPONSE BODY: ".$response->getBody();
             $v .= "\n * ATTEMPTS: ".$this->attempts;
             $this->logger->debug($v);
         }
     }
 
-    protected function isTokenExpiredCode($code)
+    /**
+     * @return string
+     */
+    protected function getTokenCacheKey(): string
     {
-        return in_array($code, [4, 5, 6, 12, 13, 14]);
+        return self::TOKEN_CACHE_KEY.'_'.md5($this->connection->login.$this->connection->pass).'_'.$this->connection->version;
     }
 
-    private function isTokenExpired($body)
+    /**
+     * @param object $body
+     * @return bool
+     */
+    private function isTokenExpired($body): bool
     {
-        return isset($body->error) && $this->isTokenExpiredCode($body->error->code);
+        return isset($body->error) && in_array($body->error->code, [4, 5, 6, 12, 13, 14], true);
     }
 }
diff --git a/src/AtolOnlineClient/Configuration.php b/src/AtolOnlineClient/Configuration.php
index 1227a85..d523a1f 100644
--- a/src/AtolOnlineClient/Configuration.php
+++ b/src/AtolOnlineClient/Configuration.php
@@ -8,14 +8,20 @@ use Symfony\Component\Validator\Mapping\ClassMetadata;
 
 class Configuration implements ConfigurationInterface
 {
-    /** @var Connection[] */
+    /**
+     * @var Connection[]
+     */
     public $connections;
 
-    /** @var boolean */
-    public $enabled;
+    /**
+     * @var boolean
+     */
+    public $enabled = true;
 
-    /** @var bool */
-    public $debug;
+    /**
+     * @var bool
+     */
+    public $debug = false;
 
     /**
      * @param ClassMetadata $metadata
diff --git a/src/AtolOnlineClient/Configuration/Connection.php b/src/AtolOnlineClient/Configuration/Connection.php
index 95e19a3..a150190 100644
--- a/src/AtolOnlineClient/Configuration/Connection.php
+++ b/src/AtolOnlineClient/Configuration/Connection.php
@@ -45,7 +45,7 @@ class Connection
     public $sno;
 
     /** @var string */
-    public $version;
+    public $version = AtolOnlineApi::API_VERSION_V3;
 
     /** @var bool */
     public $testMode = false;
diff --git a/src/AtolOnlineClient/Exception/AtolException.php b/src/AtolOnlineClient/Exception/AtolException.php
index 9ec01a5..394a7aa 100644
--- a/src/AtolOnlineClient/Exception/AtolException.php
+++ b/src/AtolOnlineClient/Exception/AtolException.php
@@ -2,7 +2,8 @@
 
 namespace AtolOnlineClient\Exception;
 
-class AtolException extends \Exception
-{
+use Exception;
 
+class AtolException extends Exception
+{
 }
diff --git a/src/AtolOnlineClient/Exception/InvalidResponseException.php b/src/AtolOnlineClient/Exception/InvalidResponseException.php
new file mode 100644
index 0000000..5365754
--- /dev/null
+++ b/src/AtolOnlineClient/Exception/InvalidResponseException.php
@@ -0,0 +1,59 @@
+<?php
+
+namespace AtolOnlineClient\Exception;
+
+/**
+ * Class InvalidResponseException
+ *
+ * @package AtolOnlineClient\Exception
+ */
+class InvalidResponseException extends AtolException
+{
+    /**
+     * @var int|null
+     */
+    protected $codeError;
+
+    /**
+     * @var string|null
+     */
+    protected $messageError;
+
+    /**
+     * @return int|null
+     */
+    public function getCodeError(): ?int
+    {
+        return $this->codeError;
+    }
+
+    /**
+     * @param int|null $codeError
+     * @return InvalidResponseException
+     */
+    public function setCodeError(?int $codeError): InvalidResponseException
+    {
+        $this->codeError = $codeError;
+
+        return $this;
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getMessageError(): ?string
+    {
+        return $this->messageError;
+    }
+
+    /**
+     * @param string|null $messageError
+     * @return InvalidResponseException
+     */
+    public function setMessageError(?string $messageError): InvalidResponseException
+    {
+        $this->messageError = $messageError;
+
+        return $this;
+    }
+}
diff --git a/src/AtolOnlineClient/Request/V4/VatReceiptRequest.php b/src/AtolOnlineClient/Request/V4/VatReceiptRequest.php
index bd0a10f..e2b4cf8 100644
--- a/src/AtolOnlineClient/Request/V4/VatReceiptRequest.php
+++ b/src/AtolOnlineClient/Request/V4/VatReceiptRequest.php
@@ -60,4 +60,4 @@ class VatReceiptRequest
     {
         return $this->sum;
     }
-}
\ No newline at end of file
+}
diff --git a/src/AtolOnlineClient/Response/Error.php b/src/AtolOnlineClient/Response/Error.php
index 173fdde..448ae24 100644
--- a/src/AtolOnlineClient/Response/Error.php
+++ b/src/AtolOnlineClient/Response/Error.php
@@ -4,6 +4,9 @@ namespace AtolOnlineClient\Response;
 
 use JMS\Serializer\Annotation as Serializer;
 
+/**
+ * @Serializer\AccessType("public_method")
+ */
 class Error
 {
 
diff --git a/src/AtolOnlineClient/Response/OperationResponse.php b/src/AtolOnlineClient/Response/OperationResponse.php
index 300ebd4..5d48f23 100644
--- a/src/AtolOnlineClient/Response/OperationResponse.php
+++ b/src/AtolOnlineClient/Response/OperationResponse.php
@@ -4,6 +4,9 @@ namespace AtolOnlineClient\Response;
 
 use JMS\Serializer\Annotation as Serializer;
 
+/**
+ * @Serializer\AccessType("public_method")
+ */
 class OperationResponse
 {
 
diff --git a/src/AtolOnlineClient/Response/Payload.php b/src/AtolOnlineClient/Response/Payload.php
index f6d73d9..f78075c 100644
--- a/src/AtolOnlineClient/Response/Payload.php
+++ b/src/AtolOnlineClient/Response/Payload.php
@@ -4,6 +4,9 @@ namespace AtolOnlineClient\Response;
 
 use JMS\Serializer\Annotation as Serializer;
 
+/**
+ * @Serializer\AccessType("public_method")
+ */
 class Payload
 {
     /**
diff --git a/tests/AtolOnlineClient/AtolOnlineApiTest.php b/tests/AtolOnlineClient/AtolOnlineApiTest.php
new file mode 100644
index 0000000..23b5af7
--- /dev/null
+++ b/tests/AtolOnlineClient/AtolOnlineApiTest.php
@@ -0,0 +1,479 @@
+<?php
+
+namespace AtolOnlineClient\AtolOnlineClient;
+
+use AtolOnlineClient\AtolOnline;
+use AtolOnlineClient\AtolOnlineApi;
+use AtolOnlineClient\Configuration\Connection;
+use AtolOnlineClient\Request\V4\PaymentReceiptRequest;
+use AtolOnlineClient\Request\V4\ReceiptRequest;
+use AtolOnlineClient\Request\V4\ServiceRequest;
+use Doctrine\Common\Cache\ArrayCache;
+use GuzzleHttp\Client;
+use GuzzleHttp\Exception\BadResponseException;
+use GuzzleHttp\Handler\MockHandler;
+use GuzzleHttp\HandlerStack;
+use GuzzleHttp\Psr7\Request;
+use GuzzleHttp\Psr7\Response;
+use PHPUnit\Framework\TestCase;
+use Psr\Log\NullLogger;
+use Psr\Log\Test\TestLogger;
+
+/**
+ * Class AtolOnlineApiTest
+ *
+ * @package AtolOnlineClient\AtolOnlineClient
+ */
+class AtolOnlineApiTest extends TestCase
+{
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::__construct
+     * @covers \AtolOnlineClient\AtolOnlineApi::setLogger
+     * @covers \AtolOnlineClient\AtolOnlineApi::setCache
+     * @covers \AtolOnlineClient\AtolOnlineApi::setVersion
+     * @covers \AtolOnlineClient\AtolOnlineApi::getVersion
+     */
+    public function testCreateApi(): void
+    {
+        $api = new AtolOnlineApi(new Client(), new Connection());
+
+        $this->assertInstanceOf(AtolOnlineApi::class, $api);
+
+        $this->assertSame(AtolOnlineApi::API_VERSION_V3, $api->getVersion());
+
+        $api->setVersion(AtolOnlineApi::API_VERSION_V4);
+        $this->assertSame(AtolOnlineApi::API_VERSION_V4, $api->getVersion());
+
+        $api->setLogger(new NullLogger());
+        $this->assertInstanceOf(NullLogger::class, $this->getProperty($api, 'logger'));
+
+        $api->setCache(new ArrayCache());
+        $this->assertInstanceOf(ArrayCache::class, $this->getProperty($api, 'cache'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::sell
+     */
+    public function testSell(): void
+    {
+        $responses = [
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+            new Response(200, [], $this->getReportSuccessReportV4()),
+        ];
+
+        $request = (new AtolOnline())->serializeOperationRequest($this->getPaymentRecepientRequest());
+
+        $response = $this->getApi($responses)->sell($request);
+
+        $this->assertSame('2ea26f17–0884–4f08–b120–306fc096a58f', json_decode($response, true)['uuid']);
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::sellRefund
+     */
+    public function testSellRefund(): void
+    {
+        $responses = [
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+            new Response(200, [], $this->getReportSuccessReportV4()),
+        ];
+
+        $request = (new AtolOnline())->serializeOperationRequest($this->getPaymentRecepientRequest());
+
+        $response = $this->getApi($responses)->sellRefund($request);
+
+        $this->assertSame('2ea26f17–0884–4f08–b120–306fc096a58f', json_decode($response, true)['uuid']);
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::checkStatus
+     */
+    public function testCheckStatusSuccessResponse(): void
+    {
+        $responses = [
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+            new Response(200, [], $this->getReportSuccessReportV4()),
+        ];
+
+        $response = $this->callMethod($this->getApi($responses), 'checkStatus', [
+            'uuid' => '2ea26f17–0884–4f08–b120–306fc096a58f',
+        ]);
+
+        $this->assertSame('2ea26f17–0884–4f08–b120–306fc096a58f', json_decode($response, true)['uuid']);
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::checkStatus
+     */
+    public function testCheckStatusBadResponse(): void
+    {
+        $responses = [
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+            new BadResponseException('', new Request('GET', 'test'), new Response(200, [], $this->getErrorResponseV4())),
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+            new Response(200, [], $this->getReportSuccessReportV4()),
+        ];
+
+        $api = $this->getApi($responses);
+        $api->setCache(new ArrayCache());
+
+        $response = $this->callMethod($api, 'checkStatus', [
+            'uuid' => '2ea26f17–0884–4f08–b120–306fc096a58f',
+        ]);
+
+        $this->assertSame('2ea26f17–0884–4f08–b120–306fc096a58f', json_decode($response, true)['uuid']);
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getUri
+     */
+    public function testGetUri(): void
+    {
+        $this->assertSame('https://online.atol.ru/possystem', $this->callMethod($this->getApi(), 'getUri'));
+        $this->assertSame('https://testonline.atol.ru/possystem', $this->callMethod($this->getApi([], true, true), 'getUri'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getToken
+     */
+    public function testGetTokenBadResponse(): void
+    {
+        $api = $this->getApi([new BadResponseException('', new Request('GET', 'test'))]);
+
+        $this->assertFalse($this->callMethod($api, 'getToken'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getToken
+     */
+    public function testGetTokenSuccessResponse(): void
+    {
+        $api = $this->getApi([new Response(200, [], $this->getTokenSuccessResponseV4())]);
+
+        $this->assertSame('fj45u923j59ju42395iu9423i59243u0', $this->callMethod($api, 'getToken'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getToken
+     */
+    public function testGetTokenErrorResponseWithLogger(): void
+    {
+        $logger = new TestLogger();
+
+        $api = $this->getApi([new Response(200, [], $this->getErrorResponseV4())]);
+        $api->setLogger($logger);
+
+        $this->assertFalse($this->callMethod($api, 'getToken'));
+        $this->assertTrue($logger->hasError('12 Неверный логин или пароль'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getToken
+     */
+    public function testGetTokenBadResponseWithLogger(): void
+    {
+        $logger = new TestLogger();
+
+        $api = $this->getApi([new BadResponseException('', new Request('GET', 'test'), new Response(200, [], $this->getErrorResponseV4()))]);
+        $api->setLogger($logger);
+
+        $this->assertFalse($this->callMethod($api, 'getToken'));
+        $this->assertTrue($logger->hasError('{"error":{"error_id":"4475d6d8d-844d-4d05-aa8b-e3dbdf3defd5","code":12,"text":"\u041d\u0435\u0432\u0435\u0440\u043d\u044b\u0439 \u043b\u043e\u0433\u0438\u043d \u0438\u043b\u0438 \u043f\u0430\u0440\u043e\u043b\u044c","type":"system"},"timestamp":"30.11.2017 17:58:53"}'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getToken
+     */
+    public function testGetTokenSuccessResponseWithCache(): void
+    {
+        $cache = new ArrayCache();
+
+        $api = $this->getApi([new Response(200, [], $this->getTokenSuccessResponseV4())]);
+        $api->setCache($cache);
+
+        $this->assertSame('fj45u923j59ju42395iu9423i59243u0', $this->callMethod($api, 'getToken'));
+        $this->assertTrue($cache->contains($this->callMethod($api, 'getTokenCacheKey')));
+
+        $this->assertSame('fj45u923j59ju42395iu9423i59243u0', $this->callMethod($api, 'getToken'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getToken
+     */
+    public function testGetTokenSuccessResponseV3(): void
+    {
+        $api = $this->getApi([new Response(200, [], $this->getTokenSuccessResponseV3())])->setVersion(AtolOnlineApi::API_VERSION_V3);
+
+        $this->assertSame('fj45u923j59ju42395iu9423i59243u0', $this->callMethod($api, 'getToken'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getToken
+     */
+    public function testGetTokenSuccessResponseV3WithCache(): void
+    {
+        $cache = new ArrayCache();
+
+        $api = $this->getApi([new Response(200, [], $this->getTokenSuccessResponseV3())])->setVersion(AtolOnlineApi::API_VERSION_V3);
+        $api->setCache($cache);
+
+        $this->assertSame('fj45u923j59ju42395iu9423i59243u0', $this->callMethod($api, 'getToken'));
+        $this->assertTrue($cache->contains($this->callMethod($api, 'getTokenCacheKey')));
+
+        $this->assertSame('fj45u923j59ju42395iu9423i59243u0', $this->callMethod($api, 'getToken'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::buildUrl
+     */
+    public function testBuildUrlWithoutToken(): void
+    {
+        $args = ['operation' => 'test'];
+
+        $this->assertSame('https://online.atol.ru/possystem/v4/group/test', $this->callMethod($this->getApi(), 'buildUrl', $args));
+        $this->assertSame('https://online.atol.ru/possystem/v3/group/test', $this->callMethod($this->getApi()->setVersion(AtolOnlineApi::API_VERSION_V3), 'buildUrl', $args));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::buildUrl
+     */
+    public function testBuildUrlWithToken(): void
+    {
+        $args = ['operation' => 'test', 'token' => 'test'];
+
+        $this->assertSame('https://online.atol.ru/possystem/v4/group/test?token=test', $this->callMethod($this->getApi(), 'buildUrl', $args));
+        $this->assertSame('https://online.atol.ru/possystem/v3/group/test?tokenid=test', $this->callMethod($this->getApi()->setVersion(AtolOnlineApi::API_VERSION_V3), 'buildUrl', $args));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::sendOperationRequest
+     */
+    public function testSendOperationRequestSuccessResponse(): void
+    {
+        $responses = [
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+            new Response(200, [], $this->getTokenSuccessResponseV4())
+        ];
+
+        $request = (new AtolOnline())->serializeOperationRequest($this->getPaymentRecepientRequest());
+
+        $response = $this->callMethod($this->getApi($responses), 'sendOperationRequest', [
+            'operation' => 'sell',
+            'data' => $request,
+        ]);
+
+        $this->assertSame('fj45u923j59ju42395iu9423i59243u0', json_decode($response, true)['token']);
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::sendOperationRequest
+     */
+    public function testSendOperationRequestBadResponse(): void
+    {
+        $responses = [
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+            new BadResponseException('', new Request('GET', 'test'), new Response(200, [], $this->getErrorResponseV4())),
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+            new Response(200, [], $this->getTokenSuccessResponseV4()),
+        ];
+
+        $request = (new AtolOnline())->serializeOperationRequest($this->getPaymentRecepientRequest());
+
+        $api = $this->getApi($responses);
+        $api->setCache(new ArrayCache());
+
+        $response = $this->callMethod($api, 'sendOperationRequest', [
+            'operation' => 'sell',
+            'data' => $request,
+        ]);
+
+        $this->assertSame('fj45u923j59ju42395iu9423i59243u0', json_decode($response, true)['token']);
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::logDebug
+     */
+    public function testLogDebug(): void
+    {
+        $logger = new TestLogger();
+
+        $api = $this->getApi();
+        $api->setLogger($logger);
+
+        $this->callMethod($api, 'logDebug', [
+            'url' => '/test',
+            'data' => 'test',
+            'response' => new Response(200, ['X-Foo' => 'Bar', 'X-Foo2' => 'Bar2'], 'test'),
+        ]);
+
+        $this->assertTrue($logger->hasDebug('* URL: /test
+ * POSTFIELDS: test
+ * RESPONSE HEADERS: X-Foo: Bar, X-Foo2: Bar2
+ * RESPONSE BODY: test
+ * ATTEMPTS: 0'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::getTokenCacheKey
+     */
+    public function testGetTokenCacheKey(): void
+    {
+        $this->assertSame('crm_fiscal_atol_online_token_68526766e6751745b52ae70b7bd3c6fe_v4', $this->callMethod($this->getApi(), 'getTokenCacheKey'));
+        $this->assertSame('crm_fiscal_atol_online_token_68526766e6751745b52ae70b7bd3c6fe_v3', $this->callMethod($this->getApi()->setVersion(AtolOnlineApi::API_VERSION_V3), 'getTokenCacheKey'));
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnlineApi::isTokenExpired
+     */
+    public function testIsTokenExpired(): void
+    {
+        $body = new \stdClass();
+        $body->error = new \stdClass();
+        $body->error->code = 4;
+
+        $this->assertTrue($this->callMethod($this->getApi(), 'isTokenExpired', ['body' => $body]));
+
+        $body = new \stdClass();
+        $this->assertFalse($this->callMethod($this->getApi(), 'isTokenExpired', ['body' => $body]));
+    }
+
+    /**
+     * @param array $responses
+     * @param bool $debug
+     * @param bool $test
+     * @return AtolOnlineApi
+     */
+    private function getApi(array $responses = [], bool $debug = true, bool $test = false): AtolOnlineApi
+    {
+        $connection = new Connection();
+        $connection->login = 'login';
+        $connection->pass = 'pass';
+        $connection->group = 'group';
+        $connection->sno = Connection::SNO_GENERAL;
+        $connection->version = AtolOnlineApi::API_VERSION_V4;
+        $connection->setDebug($debug);
+        $connection->setTestMode($test);
+
+        $mock = new MockHandler($responses);
+
+        $handler = HandlerStack::create($mock);
+
+        return new AtolOnlineApi(new Client(['handler' => $handler]), $connection);
+    }
+
+    /**
+     * @param mixed $object
+     * @param string $name
+     * @param array $args
+     * @return mixed
+     */
+    private function callMethod($object, string $name, array $args = [])
+    {
+        $reflection = new \ReflectionClass($object);
+        $method = $reflection->getMethod($name);
+        $method->setAccessible(true);
+
+        return $method->invokeArgs($object, $args);
+    }
+
+    /**
+     * @param mixed $object
+     * @param string $name
+     * @return mixed
+     */
+    private function getProperty($object, string $name)
+    {
+        $reflection = new \ReflectionClass($object);
+        $property = $reflection->getProperty($name);
+        $property->setAccessible(true);
+
+        return $property->getValue($object);
+    }
+
+    /**
+     * @return false|string
+     */
+    private function getTokenSuccessResponseV3()
+    {
+        return json_encode([
+            'token' => 'fj45u923j59ju42395iu9423i59243u0',
+            'code' => 1,
+        ]);
+    }
+
+    /**
+     * @return false|string
+     */
+    private function getTokenSuccessResponseV4()
+    {
+        return json_encode([
+            'error' => null,
+            'token' => 'fj45u923j59ju42395iu9423i59243u0',
+            'timestamp' => '30.11.2017 17:58:53',
+        ]);
+    }
+
+    /**
+     * @return false|string
+     */
+    private function getErrorResponseV4()
+    {
+        return json_encode([
+            'error' => [
+                'error_id' => '4475d6d8d-844d-4d05-aa8b-e3dbdf3defd5',
+                'code' => 12,
+                'text' => 'Неверный логин или пароль',
+                'type' => 'system',
+            ],
+            'timestamp' => '30.11.2017 17:58:53',
+        ]);
+    }
+
+    /**
+     * @return string
+     */
+    private function getReportSuccessReportV4(): string
+    {
+        return file_get_contents(__DIR__.'/../fixtures/success_response_v4_3.json');
+    }
+
+    /**
+     * @return PaymentReceiptRequest
+     */
+    private function getPaymentRecepientRequest(): PaymentReceiptRequest
+    {
+        $service = new ServiceRequest();
+        $service->setCallbackUrl('test.local');
+
+        $receipt = new ReceiptRequest();
+        $receipt->setTotal('100');
+
+        /** @var PaymentReceiptRequest $request */
+        $request = new PaymentReceiptRequest();
+        $request->setExternalId('test');
+        $request->setService($service);
+        $request->setReceipt($receipt);
+
+        return $request;
+    }
+}
diff --git a/tests/AtolOnlineClient/AtolOnlineTest.php b/tests/AtolOnlineClient/AtolOnlineTest.php
new file mode 100644
index 0000000..bbdc577
--- /dev/null
+++ b/tests/AtolOnlineClient/AtolOnlineTest.php
@@ -0,0 +1,265 @@
+<?php
+
+namespace AtolOnlineClient\Tests;
+
+use AtolOnlineClient\AtolOnline;
+use AtolOnlineClient\Configuration\Connection;
+use AtolOnlineClient\ConfigurationInterface;
+use AtolOnlineClient\Exception\InvalidResponseException;
+use AtolOnlineClient\Request\V4\PaymentReceiptRequest;
+use AtolOnlineClient\Request\V4\ReceiptRequest;
+use AtolOnlineClient\Request\V4\ServiceRequest;
+use GuzzleHttp\Client;
+use JMS\Serializer\Exception\RuntimeException;
+use JMS\Serializer\SerializerInterface;
+use PHPUnit\Framework\TestCase;
+
+class AtolOnlineTest extends TestCase
+{
+    /**
+     * @var AtolOnline
+     */
+    protected $atol;
+
+    /**
+     * @return void
+     */
+    public function setUp(): void
+    {
+        $this->atol =  new AtolOnline();
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\AtolOnline::__construct
+     */
+    public function testConstructor(): void
+    {
+        $reflection = new \ReflectionClass(get_class($this->atol));
+
+        $property = $reflection->getProperty('serializer');
+        $property->setAccessible(true);
+
+        $this->assertInstanceOf(SerializerInterface::class, $property->getValue($this->atol));
+    }
+
+    /**
+     * @covers \AtolOnlineClient\AtolOnline::createConfiguration
+     * @return void
+     */
+    public function testCreateConfiguration(): void
+    {
+        $this->assertInstanceOf(ConfigurationInterface::class, $this->atol->createConfiguration());
+    }
+
+    /**
+     * @param string $file
+     * @covers \AtolOnlineClient\AtolOnline::deserializeOperationResponse
+     * @dataProvider dataSuccessResponse
+     */
+    public function testSuccessDeserializeOperationResponse(string $file): void
+    {
+        $response = file_get_contents(__DIR__.'/../fixtures/'. $file);
+
+        $operationResponse = $this->atol->deserializeOperationResponse($response);
+
+        $this->assertEquals('12.04.2017 06:15:06', $operationResponse->getTimestamp());
+    }
+
+    /**
+     * @param string $file
+     * @covers \AtolOnlineClient\AtolOnline::deserializeOperationResponse
+     * @dataProvider dataErrorResponse
+     */
+    public function testErrorDeserializeOperationResponse(string $file): void
+    {
+        $response = file_get_contents(__DIR__.'/../fixtures/'. $file);
+
+        $operationResponse = $this->atol->deserializeOperationResponse($response);
+
+        $this->assertEquals('12.04.2017 06:15:06', $operationResponse->getTimestamp());
+        $this->assertEquals('fail', $operationResponse->getStatus());
+        $this->assertEquals(30, $operationResponse->getError()->getCode());
+        $this->assertEquals('system', $operationResponse->getError()->getType());
+
+        $this->assertEquals(
+            ' Передан некорректный UUID : "{0}". Необходимо повторить запрос с корректными данными ',
+            $operationResponse->getError()->getText()
+        );
+    }
+
+    /**
+     * @covers \AtolOnlineClient\AtolOnline::deserializeOperationResponse
+     */
+    public function testFailDeserializeOperationResponse(): void
+    {
+        $this->expectException(InvalidResponseException::class);
+
+        $this->atol->deserializeOperationResponse('<html></html>');
+    }
+
+    /**
+     * @param string $file
+     * @covers \AtolOnlineClient\AtolOnline::deserializeCheckStatusResponse
+     * @dataProvider dataSuccessResponse
+     */
+    public function testSuccessDeserializeCheckStatusResponse(string $file): void
+    {
+        $response = file_get_contents(__DIR__.'/../fixtures/'. $file);
+
+        $operationResponse = $this->atol->deserializeCheckStatusResponse($response);
+
+        $this->assertEquals('12.04.2017 06:15:06', $operationResponse->getTimestamp());
+    }
+
+    /**
+     * @covers \AtolOnlineClient\AtolOnline::deserializeCheckStatusResponse
+     */
+    public function testFailDeserializeCheckStatusResponse(): void
+    {
+        $this->expectException(InvalidResponseException::class);
+
+        $this->atol->deserializeCheckStatusResponse('<html></html>');
+    }
+
+    /**
+     * @param int|null $code
+     * @param string|null $message
+     * @param string $html
+     * @covers       \AtolOnlineClient\AtolOnline::createInvalidResponseException
+     * @dataProvider dataInvalidResponse
+     */
+    public function testCreateInvalidResponseException(?int $code, ?string $message, string $html): void
+    {
+        /** @var InvalidResponseException $exception */
+        $exception = $this->callMethod($this->atol, 'createInvalidResponseException', [
+            'response' => $html,
+            'previous' => new RuntimeException()
+        ]);
+
+        $this->assertInstanceOf(InvalidResponseException::class, $exception);
+        $this->assertEquals($code, $exception->getCodeError());
+        $this->assertEquals($message, $exception->getMessageError());
+    }
+
+    /**
+     * @covers \AtolOnlineClient\AtolOnline::serializeOperationRequest
+     */
+    public function testSerializeOperationRequest(): void
+    {
+        $service = new ServiceRequest();
+        $service->setCallbackUrl('test.local');
+
+        $receipt = new ReceiptRequest();
+        $receipt->setTotal('100');
+
+        /** @var PaymentReceiptRequest $paymentReceipt */
+        $paymentReceipt = new PaymentReceiptRequest();
+
+        $reflection = new \ReflectionClass($paymentReceipt);
+        $property = $reflection->getProperty('timestamp');
+        $property->setAccessible(true);
+        $property->setValue($paymentReceipt, 1);
+
+        $paymentReceipt->setExternalId('test');
+        $paymentReceipt->setService($service);
+        $paymentReceipt->setReceipt($receipt);
+
+        $request = $this->atol->serializeOperationRequest($paymentReceipt);
+
+        $this->assertEquals('{"external_id":"test","receipt":{"total":100},"timestamp":"1","service":{"callback_url":"test.local"}}', $request);
+    }
+
+    /**
+     * @return void
+     *
+     * @covers \AtolOnlineClient\AtolOnline::createApi
+     */
+    public function testCreateApi(): void
+    {
+        $api1 =  $this->atol->createApi(new Client(), new Connection());
+        $api2 =  $this->atol->createApi(new Client(), new Connection());
+
+        $this->assertSame($api1, $api2);
+    }
+
+    /**
+     * @return void
+     *
+     * @covers \AtolOnlineClient\AtolOnline::getApi
+     */
+    public function testGetApi(): void
+    {
+        $api1 =  $this->atol->createApi(new Client(), new Connection());
+        $api2 =  $this->atol->getApi();
+
+        $this->assertSame($api1, $api2);
+    }
+
+    /**
+     * @return array
+     */
+    public function dataSuccessResponse(): array
+    {
+        return [
+            ['success_response_v4_1.json'],
+            ['success_response_v4_2.json'],
+            ['success_response_v4_3.json'],
+        ];
+    }
+
+    /**
+     * @return array
+     */
+    public function dataErrorResponse(): array
+    {
+        return [
+            ['error_response_v3.json'],
+            ['error_response_v4.json']
+        ];
+    }
+
+    /**
+     * @return array
+     */
+    public function dataInvalidResponse(): array
+    {
+        return [
+            [
+                'code' => 404,
+                'message' => 'Not Found',
+                'html' => '<html><head><title>404 Not Found</title></head><body><center><h1>404 Not Found</h1></center><hr><center>openresty/1.15.8.1rc1</center></body></html>',
+            ],
+            [
+                'code' => 502,
+                'message' => 'Bad Gateway',
+                'html' => '<html><head><title>502 Bad Gateway</title></head><body><center><h1>502 Bad Gateway</h1></center><hr><center>nginx/1.15.8</center></body></html>',
+            ],
+            [
+                'code' => null,
+                'message' => null,
+                'html' => '<html></html>',
+            ],
+            [
+                'code' => null,
+                'message' => null,
+                'html' => '',
+            ],
+        ];
+    }
+
+    /**
+     * @param mixed $object
+     * @param string $name
+     * @param array $args
+     * @return mixed
+     */
+    private function callMethod($object, string $name, array $args = [])
+    {
+        $reflection = new \ReflectionClass($object);
+        $method = $reflection->getMethod($name);
+        $method->setAccessible(true);
+
+        return $method->invokeArgs($object, $args);
+    }
+}
diff --git a/tests/AtolOnlineClient/Configuration/ConnectionTest.php b/tests/AtolOnlineClient/Configuration/ConnectionTest.php
new file mode 100644
index 0000000..4947d09
--- /dev/null
+++ b/tests/AtolOnlineClient/Configuration/ConnectionTest.php
@@ -0,0 +1,89 @@
+<?php
+
+namespace AtolOnlineClient\AtolOnlineClient\Connection;
+
+use AtolOnlineClient\AtolOnlineApi;
+use AtolOnlineClient\Configuration\Connection;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Validator\Validation;
+
+class ConnectionTest extends TestCase
+{
+    /**
+     * @var Connection
+     */
+    private $connection;
+
+    /**
+     * @return void
+     */
+    public function setUp(): void
+    {
+        $this->connection = new Connection();
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\Configuration\Connection::setDebug
+     * @covers \AtolOnlineClient\Configuration\Connection::isDebug
+     */
+    public function testDebug(): void
+    {
+        $this->assertFalse($this->connection->isDebug());
+
+        $this->connection->setDebug(true);
+        $this->assertTrue($this->connection->isDebug());
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\Configuration\Connection::isTestMode
+     * @covers \AtolOnlineClient\Configuration\Connection::setTestMode
+     */
+    public function testTestMode(): void
+    {
+        $this->assertFalse($this->connection->isTestMode());
+
+        $this->connection->setTestMode(true);
+        $this->assertTrue($this->connection->isTestMode());
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\Configuration\Connection::getVersion
+     * @covers \AtolOnlineClient\Configuration\Connection::isVersion4
+     * @covers \AtolOnlineClient\Configuration\Connection::isVersion3
+     */
+    public function testVersion(): void
+    {
+        $this->assertEquals(AtolOnlineApi::API_VERSION_V3, $this->connection->getVersion());
+        $this->assertTrue($this->connection->isVersion3());
+
+        $this->connection->version = AtolOnlineApi::API_VERSION_V4;
+        $this->assertTrue($this->connection->isVersion4());
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\Configuration\Connection::loadValidatorMetadata
+     */
+    public function testValidator(): void
+    {
+
+        $validator = Validation::createValidatorBuilder()
+            ->addMethodMapping('loadValidatorMetadata')
+            ->getValidator();
+
+        $list = $validator->validate($this->connection);
+
+        $this->assertEquals(3, $list->count());
+
+        $this->connection->login = 'login';
+        $this->connection->pass = 'login';
+        $this->connection->group = 'group';
+
+        $list = $validator->validate($this->connection);
+
+        $this->assertEquals(0, $list->count());
+    }
+}
diff --git a/tests/AtolOnlineClient/ConfigurationTest.php b/tests/AtolOnlineClient/ConfigurationTest.php
new file mode 100644
index 0000000..ade8698
--- /dev/null
+++ b/tests/AtolOnlineClient/ConfigurationTest.php
@@ -0,0 +1,78 @@
+<?php
+
+namespace AtolOnlineClient\AtolOnlineClient;
+
+use AtolOnlineClient\Configuration;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Validator\Validation;
+
+/**
+ * Class ConfigurationTest
+ *
+ * @package AtolOnlineClient\AtolOnlineClient
+ */
+class ConfigurationTest extends TestCase
+{
+    /**
+     * @var Configuration
+     */
+    private $configuration;
+
+    public function setUp(): void
+    {
+        $this->configuration = new Configuration();
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\Configuration::isDebug
+     * @covers \AtolOnlineClient\Configuration::setDebug
+     */
+    public function testDebug(): void
+    {
+        $this->assertFalse($this->configuration->isDebug());
+
+        $this->configuration->setDebug(true);
+        $this->assertTrue($this->configuration->isDebug());
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\Configuration::isEnabled
+     * @covers \AtolOnlineClient\Configuration::setEnabled
+     */
+    public function testEnabled(): void
+    {
+        $this->assertTrue($this->configuration->isEnabled());
+
+        $this->configuration->setEnabled(false);
+        $this->assertFalse($this->configuration->isEnabled());
+    }
+
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\Configuration::loadValidatorMetadata
+     */
+    public function testValidator(): void
+    {
+
+        $validator = Validation::createValidatorBuilder()
+            ->addMethodMapping('loadValidatorMetadata')
+            ->getValidator();
+
+        $list = $validator->validate($this->configuration);
+
+        $this->assertEquals(1, $list->count());
+
+        $connection = new Configuration\Connection();
+        $connection->login = 'login';
+        $connection->pass = 'login';
+        $connection->group = 'group';
+
+        $this->configuration->connections[] = $connection;
+
+        $list = $validator->validate($this->configuration);
+
+        $this->assertEquals(0, $list->count());
+    }
+}
diff --git a/tests/AtolOnlineClient/Response/ResponseTest.php b/tests/AtolOnlineClient/Response/ResponseTest.php
new file mode 100644
index 0000000..6b71c30
--- /dev/null
+++ b/tests/AtolOnlineClient/Response/ResponseTest.php
@@ -0,0 +1,63 @@
+<?php
+
+namespace AtolOnlineClient\AtolOnlineClient\Response;
+
+use AtolOnlineClient\Response\OperationResponse;
+use JMS\Serializer\SerializerBuilder;
+use PHPUnit\Framework\TestCase;
+
+/**
+ */
+class ResponseTest extends TestCase
+{
+    /**
+     * @return void
+     * @covers \AtolOnlineClient\Response\OperationResponse
+     * @covers \AtolOnlineClient\Response\Error
+     * @covers \AtolOnlineClient\Response\Payload
+     */
+    public function testResponse(): void
+    {
+        $serializer = SerializerBuilder::create()->build();
+
+        $response = '{
+  "uuid": "4355",
+  "timestamp": "12.04.2017 06:15:06",
+  "status": "fail",
+  "error": {
+    "error_id": "475d6d8d-844d-4d05-aa8b-e3dbdf4defd6",
+    "code": 30,
+    "text": " Передан некорректный UUID : \"{0}\". Необходимо повторить запрос с корректными данными ",
+    "type": "system"
+  },
+  "payload": {
+    "total": 1598,
+    "fns_site": "www.nalog.ru",
+    "fn_number": "1110000100238211",
+    "shift_number": 23,
+    "receipt_datetime": "12.04.2017 20:16:00",
+    "fiscal_receipt_number": 6,
+    "fiscal_document_number": 133,
+    "ecr_registration_number": "0000111118041361",
+    "fiscal_document_attribute": 3449555941
+  },
+  "group_code": " MyCompany_MyShop",
+  "daemon_code": "prod–agent–1",
+  "device_code": "KSR13.00–1–11",
+  "external_id": "TRF10601_1",
+  "callback_url": ""
+}';
+        $response = $serializer->deserialize(
+            $response,
+            OperationResponse::class,
+            'json'
+        );
+
+        $serializer->serialize(
+            $response,
+            'json'
+        );
+
+        $this->assertTrue(true);
+    }
+}
diff --git a/tests/AtolOnlineClient/Tests/AtolOnlineTest.php b/tests/AtolOnlineClient/Tests/AtolOnlineTest.php
deleted file mode 100644
index ad5249d..0000000
--- a/tests/AtolOnlineClient/Tests/AtolOnlineTest.php
+++ /dev/null
@@ -1,46 +0,0 @@
-<?php
-
-namespace AtolOnlineClient\Tests;
-
-use AtolOnlineClient\AtolOnline;
-use AtolOnlineClient\Configuration;
-use AtolOnlineClient\Response\OperationResponse;
-use PHPUnit\Framework\TestCase;
-
-class AtolOnlineTest extends TestCase
-{
-
-    public function testCreateConfiguration()
-    {
-        $atol = new AtolOnline();
-        $this->assertInstanceOf(Configuration::class, $atol->createConfiguration());
-    }
-
-
-    /**
-     * @dataProvider dataSellErrorResponse
-     */
-    public function testDeserializeOperationResponse($file)
-    {
-        $response = file_get_contents(__DIR__ . '/data/'. $file);
-        $atol = new AtolOnline();
-        $operationResponse = $atol->deserializeOperationResponse($response);
-        $this->assertInstanceOf(OperationResponse::class, $operationResponse);
-        $this->assertEquals('12.04.2017 06:15:06', $operationResponse->getTimestamp());
-        $this->assertEquals('fail', $operationResponse->getStatus());
-        $this->assertEquals(30, $operationResponse->getError()->getCode());
-        $this->assertEquals('system', $operationResponse->getError()->getType());
-        $this->assertEquals(
-            ' Передан некорректный UUID : "{0}". Необходимо повторить запрос с корректными данными ',
-            $operationResponse->getError()->getText()
-        );
-    }
-
-    public function dataSellErrorResponse()
-    {
-        return [
-            ['sell_error_response_v3.json'],
-            ['sell_error_response_v3.json']
-        ];
-    }
-}
diff --git a/bootstrap.php b/tests/bootstrap.php
similarity index 79%
rename from bootstrap.php
rename to tests/bootstrap.php
index 8c24c52..6559848 100644
--- a/bootstrap.php
+++ b/tests/bootstrap.php
@@ -1,13 +1,13 @@
 <?php
+
 use Composer\Autoload\ClassLoader;
 use Doctrine\Common\Annotations\AnnotationRegistry;
 
 /**
  * @var ClassLoader $loader
  */
-$loader = require __DIR__.'/vendor/autoload.php';
+$loader = require __DIR__.'/../vendor/autoload.php';
 
 AnnotationRegistry::registerLoader('class_exists');
 
-
 return $loader;
diff --git a/tests/AtolOnlineClient/Tests/data/sell_error_response_v3.json b/tests/fixtures/error_response_v3.json
similarity index 100%
rename from tests/AtolOnlineClient/Tests/data/sell_error_response_v3.json
rename to tests/fixtures/error_response_v3.json
diff --git a/tests/AtolOnlineClient/Tests/data/sell_error_response_v4.json b/tests/fixtures/error_response_v4.json
similarity index 100%
rename from tests/AtolOnlineClient/Tests/data/sell_error_response_v4.json
rename to tests/fixtures/error_response_v4.json
diff --git a/tests/fixtures/success_response_v4_1.json b/tests/fixtures/success_response_v4_1.json
new file mode 100644
index 0000000..a7517bc
--- /dev/null
+++ b/tests/fixtures/success_response_v4_1.json
@@ -0,0 +1,5 @@
+{
+  "error": null,
+  "token": "fj45u923j59ju42395iu9423i59243u0",
+  "timestamp": "12.04.2017 06:15:06"
+}
diff --git a/tests/fixtures/success_response_v4_2.json b/tests/fixtures/success_response_v4_2.json
new file mode 100644
index 0000000..04837ab
--- /dev/null
+++ b/tests/fixtures/success_response_v4_2.json
@@ -0,0 +1,6 @@
+{
+  "uuid": "2ea26f17–0884–4f08–b120–306fc096a58f",
+  "timestamp": "12.04.2017 06:15:06",
+  "error": null,
+  "status": "wait"
+}
diff --git a/tests/fixtures/success_response_v4_3.json b/tests/fixtures/success_response_v4_3.json
new file mode 100644
index 0000000..f872274
--- /dev/null
+++ b/tests/fixtures/success_response_v4_3.json
@@ -0,0 +1,22 @@
+{
+  "uuid": "2ea26f17–0884–4f08–b120–306fc096a58f",
+  "error": null,
+  "status": "done",
+  "payload": {
+    "total": 1598,
+    "fns_site": "www.nalog.ru",
+    "fn_number": "1110000100238211",
+    "shift_number": 23,
+    "receipt_datetime": "12.04.2017 20:16:00",
+    "fiscal_receipt_number": 6,
+    "fiscal_document_number": 133,
+    "ecr_registration_number": "0000111118041361",
+    "fiscal_document_attribute": 3449555941
+  },
+  "timestamp": "12.04.2017 06:15:06",
+  "group_code": "MyCompany_MyShop",
+  "daemon_code": "prod–agent–1",
+  "device_code": "KSR13.00–1–11",
+  "external_id": "TRF10601_1",
+  "callback_url": ""
+}