diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
new file mode 100644
index 0000000..e9229c0
--- /dev/null
+++ b/.github/workflows/run-tests.yml
@@ -0,0 +1,47 @@
+name: Unit Tests
+
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - "*"
+  schedule:
+  - cron: '0 0 * * *'
+
+jobs:
+  php-tests:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    env:
+      COMPOSER_NO_INTERACTION: 1
+
+    strategy:
+      matrix:
+        php: [8.1, 8.0, 7.4, 7.3, 7.2]
+        dependency-version: [prefer-lowest, prefer-stable]
+
+    name: P${{ matrix.php }} - ${{ matrix.dependency-version }}
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v2
+
+    - name: Setup PHP
+      uses: shivammathur/setup-php@v2
+      with:
+        php-version: ${{ matrix.php }}
+        coverage: none
+        tools: composer:v2
+
+    - name: Install dependencies
+      run: |
+        composer update --${{ matrix.dependency-version }} --prefer-dist --no-progress
+
+    - name: Execute Unit Tests
+      run: composer test
+      
+    - name: Check Code Style
+      run: composer check-style
+      if: ${{ matrix.dependency-version == 'prefer-stable' }}
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 77109ff..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,33 +0,0 @@
-language: php
-
-php:
-  - 5.4
-  - 5.5
-  - 5.6
-  - 7.0
-  - 7.1
-  - hhvm
-
-env:
-  global:
-    - setup=basic
-
-matrix:
-  include:
-    - php: 5.3
-      env: setup=lowest
-      dist: precise
-    - php: 5.5
-      env: setup=stable
-
-sudo: false
-
-before_install:
-  - travis_retry composer self-update
-
-install:
-  - if [[ $setup = 'basic' ]]; then travis_retry composer install --no-interaction --prefer-dist; fi
-  - if [[ $setup = 'stable' ]]; then travis_retry composer update --prefer-dist --no-interaction --prefer-stable; fi
-  - if [[ $setup = 'lowest' ]]; then travis_retry composer update --prefer-dist --no-interaction --prefer-lowest --prefer-stable; fi
-
-script: vendor/bin/phpcs --standard=PSR2 src && vendor/bin/phpunit --coverage-text
diff --git a/README.md b/README.md
index f9c29b6..8d70713 100644
--- a/README.md
+++ b/README.md
@@ -2,30 +2,21 @@
 
 **PayPal driver for the Omnipay PHP payment processing library**
 
-[![Build Status](https://travis-ci.org/thephpleague/omnipay-paypal.png?branch=master)](https://travis-ci.org/thephpleague/omnipay-paypal)
+[![Unit Tests](https://github.com/thephpleague/omnipay-paypal/actions/workflows/run-tests.yml/badge.svg)](https://github.com/thephpleague/omnipay-paypal/actions/workflows/run-tests.yml)
 [![Latest Stable Version](https://poser.pugx.org/omnipay/paypal/version.png)](https://packagist.org/packages/omnipay/paypal)
 [![Total Downloads](https://poser.pugx.org/omnipay/paypal/d/total.png)](https://packagist.org/packages/omnipay/paypal)
 
 [Omnipay](https://github.com/thephpleague/omnipay) is a framework agnostic, multi-gateway payment
-processing library for PHP 5.3+. This package implements PayPal support for Omnipay.
+processing library for PHP. This package implements PayPal support for Omnipay.
 
 ## Installation
 
-Omnipay is installed via [Composer](http://getcomposer.org/). To install, simply add it
-to your `composer.json` file:
+Omnipay is installed via [Composer](http://getcomposer.org/). To install, simply require `league/omnipay` and `omnipay/paypal` with Composer:
 
-```json
-{
-    "require": {
-        "omnipay/paypal": "~2.0"
-    }
-}
+```
+composer require league/omnipay omnipay/paypal
 ```
 
-And run composer to update your dependencies:
-
-    $ curl -s http://getcomposer.org/installer | php
-    $ php composer.phar update
 
 ## Basic Usage
 
diff --git a/composer.json b/composer.json
index d7e259d..100c82d 100644
--- a/composer.json
+++ b/composer.json
@@ -27,15 +27,22 @@
         "psr-4": { "Omnipay\\PayPal\\" : "src/" }
     },
     "require": {
-        "omnipay/common": "~2.0"
+        "php": "^7.2|^8.0",
+        "omnipay/common": "^3"
     },
     "require-dev": {
-        "omnipay/tests": "~2.0"
+        "omnipay/tests": "^4.1.2",
+        "squizlabs/php_codesniffer": "^3"
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "2.3.x-dev"
+            "dev-master": "3.0.x-dev"
         }
     },
-    "minimum-stability": "dev"
+    "scripts": {
+        "test": "phpunit",
+        "check-style": "phpcs -p --standard=PSR2 src/",
+        "fix-style": "phpcbf -p --standard=PSR2 src/"
+    },
+    "prefer-stable": true
 }
diff --git a/grumphp.yml b/grumphp.yml
new file mode 100644
index 0000000..4b767a0
--- /dev/null
+++ b/grumphp.yml
@@ -0,0 +1,15 @@
+parameters:
+    git_dir: .
+    bin_dir: vendor/bin
+    tasks:
+        phpunit:
+            config_file: ~
+            testsuite: ~
+            group: []
+            always_execute: false
+        phpcs:
+            standard: PSR2
+            warning_severity: ~
+            ignore_patterns:
+              - tests/
+            triggered_by: [php]
\ No newline at end of file
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index a35b736..535809e 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -14,9 +14,6 @@
             <directory>./tests/</directory>
         </testsuite>
     </testsuites>
-    <listeners>
-        <listener class="Mockery\Adapter\Phpunit\TestListener" file="vendor/mockery/mockery/library/Mockery/Adapter/Phpunit/TestListener.php" />
-    </listeners>
     <filter>
         <whitelist>
             <directory>./src</directory>
diff --git a/src/Message/AbstractRequest.php b/src/Message/AbstractRequest.php
index 0885093..532736c 100644
--- a/src/Message/AbstractRequest.php
+++ b/src/Message/AbstractRequest.php
@@ -24,11 +24,11 @@
  *   Account; it also gives the merchant the flexibility to change payment
  *   processors without having to re-do their technical integration. When using
  *   PayPal Payments Pro (Payflow Edition) using Payflow Gateway integration,
- *   merchants can use Transparent Redirect feature to help manage PCI compliance. 
+ *   merchants can use Transparent Redirect feature to help manage PCI compliance.
  *
  * @link https://developer.paypal.com/docs/classic/products/payflow-gateway/
  * @link https://developer.paypal.com/docs/classic/express-checkout/gs_expresscheckout/
- * @link https://developer.paypal.com/docs/classic/products/ppp-payflow-edition/ 
+ * @link https://developer.paypal.com/docs/classic/products/ppp-payflow-edition/
  * @link https://devtools-paypal.com/integrationwizard/
  * @link http://paypal.github.io/sdk/
  */
@@ -38,6 +38,11 @@ abstract class AbstractRequest extends \Omnipay\Common\Message\AbstractRequest
 
     protected $liveEndpoint = 'https://api-3t.paypal.com/nvp';
     protected $testEndpoint = 'https://api-3t.sandbox.paypal.com/nvp';
+    
+    /**
+     * @var bool
+     */
+    protected $negativeAmountAllowed = true;
 
     public function getUsername()
     {
@@ -320,11 +325,9 @@ protected function getItemData()
 
     public function sendData($data)
     {
-        $httpRequest = $this->httpClient->post($this->getEndpoint(), null, http_build_query($data, '', '&'));
-        $httpRequest->getCurlOptions()->set(CURLOPT_SSLVERSION, 6); // CURL_SSLVERSION_TLSv1_2 for libcurl < 7.35
-        $httpResponse = $httpRequest->send();
+        $httpResponse = $this->httpClient->request('POST', $this->getEndpoint(), [], http_build_query($data, '', '&'));
 
-        return $this->createResponse($httpResponse->getBody());
+        return $this->createResponse($httpResponse->getBody()->getContents());
     }
 
     protected function getEndpoint()
diff --git a/src/Message/AbstractRestRequest.php b/src/Message/AbstractRestRequest.php
index 19ef31e..8a9dbe0 100644
--- a/src/Message/AbstractRestRequest.php
+++ b/src/Message/AbstractRestRequest.php
@@ -62,6 +62,29 @@ abstract class AbstractRestRequest extends \Omnipay\Common\Message\AbstractReque
      */
     protected $payerId = null;
 
+    protected $referrerCode;
+
+    /**
+     * @var bool
+     */
+    protected $negativeAmountAllowed = true;
+    
+    /**
+     * @return string
+     */
+    public function getReferrerCode()
+    {
+        return $this->referrerCode;
+    }
+
+    /**
+     * @param string $referrerCode
+     */
+    public function setReferrerCode($referrerCode)
+    {
+        $this->referrerCode = $referrerCode;
+    }
+
     public function getClientId()
     {
         return $this->getParameter('clientId');
@@ -122,39 +145,15 @@ protected function getEndpoint()
 
     public function sendData($data)
     {
-        // don't throw exceptions for 4xx errors
-        $this->httpClient->getEventDispatcher()->addListener(
-            'request.error',
-            function ($event) {
-                if ($event['response']->isClientError()) {
-                    $event->stopPropagation();
-                }
-            }
-        );
 
         // Guzzle HTTP Client createRequest does funny things when a GET request
         // has attached data, so don't send the data if the method is GET.
         if ($this->getHttpMethod() == 'GET') {
-            $httpRequest = $this->httpClient->createRequest(
-                $this->getHttpMethod(),
-                $this->getEndpoint() . '?' . http_build_query($data),
-                array(
-                    'Accept' => 'application/json',
-                    'Authorization' => 'Bearer ' . $this->getToken(),
-                    'Content-type' => 'application/json',
-                )
-            );
+            $requestUrl = $this->getEndpoint() . '?' . http_build_query($data);
+            $body = null;
         } else {
-            $httpRequest = $this->httpClient->createRequest(
-                $this->getHttpMethod(),
-                $this->getEndpoint(),
-                array(
-                    'Accept' => 'application/json',
-                    'Authorization' => 'Bearer ' . $this->getToken(),
-                    'Content-type' => 'application/json',
-                ),
-                $this->toJSON($data)
-            );
+            $body = $this->toJSON($data);
+            $requestUrl = $this->getEndpoint();
         }
 
         // Might be useful to have some debug code here, PayPal especially can be
@@ -163,11 +162,20 @@ function ($event) {
         // echo "Data == " . json_encode($data) . "\n";
 
         try {
-            $httpRequest->getCurlOptions()->set(CURLOPT_SSLVERSION, 6); // CURL_SSLVERSION_TLSv1_2 for libcurl < 7.35
-            $httpResponse = $httpRequest->send();
+            $httpResponse = $this->httpClient->request(
+                $this->getHttpMethod(),
+                $this->getEndpoint(),
+                array(
+                    'Accept' => 'application/json',
+                    'Authorization' => 'Bearer ' . $this->getToken(),
+                    'Content-type' => 'application/json',
+                    'PayPal-Partner-Attribution-Id' => $this->getReferrerCode(),
+                ),
+                $body
+            );
             // Empty response body should be parsed also as and empty array
-            $body = $httpResponse->getBody(true);
-            $jsonToArrayResponse = !empty($body) ? $httpResponse->json() : array();
+            $body = (string) $httpResponse->getBody()->getContents();
+            $jsonToArrayResponse = !empty($body) ? json_decode($body, true) : array();
             return $this->response = $this->createResponse($jsonToArrayResponse, $httpResponse->getStatusCode());
         } catch (\Exception $e) {
             throw new InvalidResponseException(
diff --git a/src/Message/RestAuthorizeRequest.php b/src/Message/RestAuthorizeRequest.php
index 8694df0..19762f9 100644
--- a/src/Message/RestAuthorizeRequest.php
+++ b/src/Message/RestAuthorizeRequest.php
@@ -230,6 +230,7 @@ public function getData()
                         'total' => $this->getAmount(),
                         'currency' => $this->getCurrency(),
                     ),
+                    'invoice_number' => $this->getTransactionId()
                 )
             ),
             'experience_profile_id' => $this->getExperienceProfileId()
diff --git a/src/Message/RestCompletePurchaseRequest.php b/src/Message/RestCompletePurchaseRequest.php
index b246fce..4603755 100644
--- a/src/Message/RestCompletePurchaseRequest.php
+++ b/src/Message/RestCompletePurchaseRequest.php
@@ -29,8 +29,8 @@
  *
  *   // Once the transaction has been approved, we need to complete it.
  *   $transaction = $gateway->completePurchase(array(
- *       'payer_id'             => $payer_id,
- *       'transactionReference' => $sale_id,
+ *       'payer_id'             => $payerId,
+ *       'transactionReference' => $paymentId,
  *   ));
  *   $response = $transaction->send();
  *   if ($response->isSuccessful()) {
diff --git a/src/Message/RestCreateWebhookRequest.php b/src/Message/RestCreateWebhookRequest.php
new file mode 100644
index 0000000..24842ef
--- /dev/null
+++ b/src/Message/RestCreateWebhookRequest.php
@@ -0,0 +1,66 @@
+<?php
+
+namespace Omnipay\PayPal\Message;
+
+final class RestCreateWebhookRequest extends AbstractRestRequest
+{
+    /**
+     * @inheritDoc
+     */
+    public function getData()
+    {
+        return [
+            'event_types' => \array_map(
+                function ($value) {
+                    return ['name' => $value];
+                },
+                $this->getEventTypes()
+            ),
+            'url' => $this->getUrl(),
+        ];
+    }
+
+    /**
+     * @return array
+     */
+    public function getEventTypes()
+    {
+        return $this->getParameter('event_types') ?: [];
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function getEndpoint()
+    {
+        return parent::getEndpoint().'/notifications/webhooks';
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getUrl()
+    {
+        return $this->getParameter('webhook_url');
+    }
+
+    /**
+     * @param array $eventTypes
+     *
+     * @return $this
+     */
+    public function setEventTypes(array $eventTypes)
+    {
+        return $this->setParameter('event_types', $eventTypes);
+    }
+
+    /**
+     * @param string $url
+     *
+     * @return $this
+     */
+    public function setUrl($url)
+    {
+        return $this->setParameter('webhook_url', $url);
+    }
+}
diff --git a/src/Message/RestListWebhooksRequest.php b/src/Message/RestListWebhooksRequest.php
new file mode 100755
index 0000000..30a67a0
--- /dev/null
+++ b/src/Message/RestListWebhooksRequest.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace Omnipay\PayPal\Message;
+
+/**
+ * PayPal REST List Webhooks request
+ *
+ * @link https://developer.paypal.com/docs/api/webhooks/#webhooks_get-all
+ */
+final class RestListWebhooksRequest extends AbstractRestRequest
+{
+    /**
+     * @inheritDoc
+     */
+    public function getData()
+    {
+        return [];
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function getEndpoint()
+    {
+        return parent::getEndpoint().'/notifications/webhooks';
+    }
+
+    /**
+     * Get HTTP Method.
+     *
+     * @return string
+     */
+    protected function getHttpMethod()
+    {
+        return 'GET';
+    }
+}
diff --git a/src/Message/RestTokenRequest.php b/src/Message/RestTokenRequest.php
index 635cf3e..b368f5a 100644
--- a/src/Message/RestTokenRequest.php
+++ b/src/Message/RestTokenRequest.php
@@ -30,27 +30,19 @@ protected function getEndpoint()
 
     public function sendData($data)
     {
-        // don't throw exceptions for 4xx errors
-        $this->httpClient->getEventDispatcher()->addListener(
-            'request.error',
-            function ($event) {
-                if ($event['response']->isClientError()) {
-                    $event->stopPropagation();
-                }
-            }
-        );
-
-        $httpRequest = $this->httpClient->createRequest(
+        $body = $data ? http_build_query($data, '', '&') : null;
+        $httpResponse = $this->httpClient->request(
             $this->getHttpMethod(),
             $this->getEndpoint(),
-            array('Accept' => 'application/json'),
-            $data
+            array(
+                'Accept' => 'application/json',
+                'Authorization' => 'Basic ' . base64_encode("{$this->getClientId()}:{$this->getSecret()}"),
+            ),
+            $body
         );
-
-        $httpResponse = $httpRequest->setAuth($this->getClientId(), $this->getSecret())->send();
         // Empty response body should be parsed also as and empty array
-        $body = $httpResponse->getBody(true);
-        $jsonToArrayResponse = !empty($body) ? $httpResponse->json() : array();
+        $body = (string) $httpResponse->getBody()->getContents();
+        $jsonToArrayResponse = !empty($body) ? json_decode($body, true) : array();
         return $this->response = new RestResponse($this, $jsonToArrayResponse, $httpResponse->getStatusCode());
     }
 }
diff --git a/src/Message/RestVerifyWebhookSignatureRequest.php b/src/Message/RestVerifyWebhookSignatureRequest.php
new file mode 100644
index 0000000..f96c6a3
--- /dev/null
+++ b/src/Message/RestVerifyWebhookSignatureRequest.php
@@ -0,0 +1,170 @@
+<?php
+
+namespace Omnipay\PayPal\Message;
+
+/**
+ * https://developer.paypal.com/docs/api/webhooks/#verify-webhook-signature
+ */
+final class RestVerifyWebhookSignatureRequest extends AbstractRestRequest
+{
+    /**
+     * @return string
+     */
+    public function getAuthAlgo()
+    {
+        return $this->getParameter('auth_algo');
+    }
+
+    /**
+     * @return string
+     */
+    public function getCertUrl()
+    {
+        return $this->getParameter('cert_url');
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function getData()
+    {
+        return [
+            'transmission_id' => $this->getTransmissionId(),
+            'auth_algo' => $this->getAuthAlgo(),
+            'cert_url' => $this->getCertUrl(),
+            'transmission_sig' => $this->getTransmissionSig(),
+            'transmission_time' => $this->getTransmissionTime(),
+            'webhook_event' => $this->getWebhookEvent(),
+            'webhook_id' => $this->getWebhookId(),
+        ];
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function getEndpoint()
+    {
+        return parent::getEndpoint().'/notifications/verify-webhook-signature';
+    }
+
+    /**
+     * @return string
+     */
+    public function getTransmissionId()
+    {
+        return $this->getParameter('transmission_id');
+    }
+
+    /**
+     * @return string
+     */
+    public function getTransmissionSig()
+    {
+        return $this->getParameter('transmission_sig');
+    }
+
+    /**
+     * @return string
+     */
+    public function getTransmissionTime()
+    {
+        return $this->getParameter('transmission_time');
+    }
+
+    /**
+     * @return string
+     */
+    public function getWebhookEvent()
+    {
+        return $this->getParameter('webhook_event');
+    }
+
+    /**
+     * @return string
+     */
+    public function getWebhookId()
+    {
+        return $this->getParameter('webhook_id');
+    }
+
+    /**
+     * @param string $authAlgo
+     *
+     * @return $this
+     */
+    public function setAuthAlgo($authAlgo)
+    {
+        return $this->setParameter('auth_algo', $authAlgo);
+    }
+
+    /**
+     * @param string $certUrl
+     *
+     * @return $this
+     */
+    public function setCertUrl($certUrl)
+    {
+        return $this->setParameter('cert_url', $certUrl);
+    }
+
+    /**
+     * @param string $transmissionId
+     *
+     * @return $this
+     */
+    public function setTransmissionId($transmissionId)
+    {
+        return $this->setParameter('transmission_id', $transmissionId);
+    }
+
+    /**
+     * @param string $transmissionSig
+     *
+     * @return $this
+     */
+    public function setTransmissionSig($transmissionSig)
+    {
+        return $this->setParameter('transmission_sig', $transmissionSig);
+    }
+
+    /**
+     * @param string $transmissionTime
+     *
+     * @return $this
+     */
+    public function setTransmissionTime($transmissionTime)
+    {
+        return $this->setParameter('transmission_time', $transmissionTime);
+    }
+
+    /**
+     * @param array $webhookEvent
+     *
+     * @return $this
+     */
+    public function setWebhookEvent(array $webhookEvent)
+    {
+        return $this->setParameter('webhook_event', $webhookEvent);
+    }
+
+    /**
+     * @param string $webhookId
+     *
+     * @return $this
+     */
+    public function setWebhookId($webhookId)
+    {
+        return $this->setParameter('webhook_id', $webhookId);
+    }
+
+    /**
+     * @param $data
+     * @param $statusCode
+     *
+     * @return RestVerifyWebhookSignatureResponse
+     */
+    protected function createResponse($data, $statusCode)
+    {
+        return $this->response = new RestVerifyWebhookSignatureResponse($this, $data, $statusCode);
+    }
+}
diff --git a/src/Message/RestVerifyWebhookSignatureResponse.php b/src/Message/RestVerifyWebhookSignatureResponse.php
new file mode 100644
index 0000000..96d54d3
--- /dev/null
+++ b/src/Message/RestVerifyWebhookSignatureResponse.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Omnipay\PayPal\Message;
+
+/**
+ * https://developer.paypal.com/docs/api/webhooks/#verify-webhook-signature
+ */
+final class RestVerifyWebhookSignatureResponse extends RestResponse
+{
+    /**
+     * @return bool
+     */
+    public function isSuccessful()
+    {
+        if (!parent::isSuccessful()) {
+            return false;
+        }
+
+        return 'SUCCESS' === $this->getVerificationStatus();
+    }
+
+    /**
+     * The status of the signature verification. Value is `SUCCESS` or `FAILURE`.
+     *
+     * @return string
+     */
+    public function getVerificationStatus()
+    {
+        return $this->data['verification_status'];
+    }
+}
diff --git a/src/RestGateway.php b/src/RestGateway.php
index 7013053..d6ae4f3 100644
--- a/src/RestGateway.php
+++ b/src/RestGateway.php
@@ -9,6 +9,9 @@
 use Omnipay\PayPal\Message\ProAuthorizeRequest;
 use Omnipay\PayPal\Message\CaptureRequest;
 use Omnipay\PayPal\Message\RefundRequest;
+use Omnipay\PayPal\Message\RestCreateWebhookRequest;
+use Omnipay\PayPal\Message\RestListWebhooksRequest;
+use Omnipay\PayPal\Message\RestVerifyWebhookSignatureRequest;
 
 /**
  * PayPal Pro Class using REST API
@@ -416,6 +419,16 @@ public function completePurchase(array $parameters = array())
         return $this->createRequest('\Omnipay\PayPal\Message\RestCompletePurchaseRequest', $parameters);
     }
 
+    /**
+     * @param array $parameters
+     *
+     * @return RestCreateWebhookRequest
+     */
+    public function createWebhook(array $parameters = [])
+    {
+        return $this->createRequest(RestCreateWebhookRequest::class, $parameters);
+    }
+
     // TODO: Update a payment resource https://developer.paypal.com/docs/api/#update-a-payment-resource
 
     //
@@ -710,6 +723,26 @@ public function searchTransaction(array $parameters = array())
         return $this->createRequest('\Omnipay\PayPal\Message\RestSearchTransactionRequest', $parameters);
     }
 
+    /**
+     * @param array $parameters
+     *
+     * @return RestListWebhooksRequest
+     */
+    public function listWebhooks(array $parameters = [])
+    {
+        return $this->createRequest(RestListWebhooksRequest::class, $parameters);
+    }
+
+    /**
+     * @param array $parameters
+     *
+     * @return RestVerifyWebhookSignatureRequest
+     */
+    public function verifyWebhookSignature(array $parameters = [])
+    {
+        return $this->createRequest(RestVerifyWebhookSignatureRequest::class, $parameters);
+    }
+
     // TODO: Update an agreement
     // TODO: Retrieve an agreement
     // TODO: Set outstanding agreement amounts
diff --git a/tests/ExpressGatewayTest.php b/tests/ExpressGatewayTest.php
index 186f692..9721f4a 100644
--- a/tests/ExpressGatewayTest.php
+++ b/tests/ExpressGatewayTest.php
@@ -21,7 +21,7 @@ class ExpressGatewayTest extends GatewayTestCase
      */
     protected $voidOptions;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
@@ -170,7 +170,7 @@ public function testCompletePurchaseHttpOptions()
 
         $response = $this->gateway->completePurchase(array(
             'amount' => '10.00',
-            'currency' => 'BYR',
+            'currency' => 'EUR',
         ))->send();
 
         $httpRequests = $this->getMockedRequests();
@@ -192,7 +192,7 @@ public function testCompletePurchaseCustomOptions()
 
         $response = $this->gateway->completePurchase(array(
             'amount' => '10.00',
-            'currency' => 'BYR',
+            'currency' => 'EUR',
             'token' => 'CUSTOM_TOKEN',
             'payerid' => 'CUSTOM_PAYERID',
         ))->send();
diff --git a/tests/ExpressInContextGatewayTest.php b/tests/ExpressInContextGatewayTest.php
index b1a0b79..cfc5f86 100644
--- a/tests/ExpressInContextGatewayTest.php
+++ b/tests/ExpressInContextGatewayTest.php
@@ -21,7 +21,7 @@ class ExpressInContextGatewayTest extends GatewayTestCase
      */
     protected $voidOptions;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
diff --git a/tests/Message/CaptureRequestTest.php b/tests/Message/CaptureRequestTest.php
index 104ebd6..f68f8f8 100644
--- a/tests/Message/CaptureRequestTest.php
+++ b/tests/Message/CaptureRequestTest.php
@@ -12,7 +12,7 @@ class CaptureRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/ExpressAuthorizeRequestTest.php b/tests/Message/ExpressAuthorizeRequestTest.php
index 1b9b5fe..e3913d8 100644
--- a/tests/Message/ExpressAuthorizeRequestTest.php
+++ b/tests/Message/ExpressAuthorizeRequestTest.php
@@ -3,6 +3,7 @@
 namespace Omnipay\PayPal\Message;
 
 use Omnipay\Common\CreditCard;
+use Omnipay\Common\Exception\InvalidRequestException;
 use Omnipay\PayPal\Message\ExpressAuthorizeRequest;
 use Omnipay\PayPal\Support\InstantUpdateApi\BillingAgreement;
 use Omnipay\PayPal\Support\InstantUpdateApi\ShippingOption;
@@ -15,7 +16,7 @@ class ExpressAuthorizeRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
@@ -306,10 +307,8 @@ public function testDataWithCallbackAndNoDefaultShippingOption()
             'shippingOptions' => $shippingOptions,
         )));
 
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            'One of the supplied shipping options must be set as default'
-        );
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage('One of the supplied shipping options must be set as default');
 
         $this->request->getData();
     }
@@ -321,10 +320,8 @@ public function testNoAmount()
 
         $this->request->initialize($baseData);
 
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            'The amount parameter is required'
-        );
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage('The amount parameter is required');
 
         $this->request->getData();
     }
@@ -337,10 +334,8 @@ public function testAmountButNoReturnUrl()
 
         $this->request->initialize($baseData);
 
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            'The returnUrl parameter is required'
-        );
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage('The returnUrl parameter is required');
 
         $this->request->getData();
     }
@@ -368,7 +363,7 @@ public function testBadCallbackConfiguration()
         // from the docblock on this exception -
         // Thrown when a request is invalid or missing required fields.
         // callback has been set but no shipping options so expect one of these:
-        $this->setExpectedException('\Omnipay\Common\Exception\InvalidRequestException');
+        $this->expectException(InvalidRequestException::class);
 
         $this->request->getData();
     }
@@ -413,10 +408,8 @@ public function testGetDataWithBillingAgreementOptionalParameters()
      */
     public function testGetDataWithBillingAgreementWrongPaymentType()
     {
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            "The 'paymentType' parameter can be only 'Any' or 'InstantOnly'"
-        );
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage("The 'paymentType' parameter can be only 'Any' or 'InstantOnly'");
 
         $billingAgreement = new BillingAgreement(false, 'Some Stuff', 'BadType', 'Some custom annotation');
     }
diff --git a/tests/Message/ExpressCompleteAuthorizeRequestTest.php b/tests/Message/ExpressCompleteAuthorizeRequestTest.php
index a2f8c27..f61090e 100644
--- a/tests/Message/ExpressCompleteAuthorizeRequestTest.php
+++ b/tests/Message/ExpressCompleteAuthorizeRequestTest.php
@@ -12,7 +12,7 @@ class ExpressCompleteAuthorizeRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
 
diff --git a/tests/Message/ExpressCompletePurchaseRequestTest.php b/tests/Message/ExpressCompletePurchaseRequestTest.php
index 87345a2..fb8de02 100644
--- a/tests/Message/ExpressCompletePurchaseRequestTest.php
+++ b/tests/Message/ExpressCompletePurchaseRequestTest.php
@@ -12,7 +12,7 @@ class ExpressCompletePurchaseRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
 
diff --git a/tests/Message/ExpressFetchCheckoutRequestTest.php b/tests/Message/ExpressFetchCheckoutRequestTest.php
index 8d94e1c..5b85df5 100644
--- a/tests/Message/ExpressFetchCheckoutRequestTest.php
+++ b/tests/Message/ExpressFetchCheckoutRequestTest.php
@@ -12,7 +12,7 @@ class ExpressFetchCheckoutRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
 
diff --git a/tests/Message/ExpressInContextAuthorizeRequestTest.php b/tests/Message/ExpressInContextAuthorizeRequestTest.php
index 8471fb0..a5cb73f 100644
--- a/tests/Message/ExpressInContextAuthorizeRequestTest.php
+++ b/tests/Message/ExpressInContextAuthorizeRequestTest.php
@@ -3,6 +3,7 @@
 namespace Omnipay\PayPal\Message;
 
 use Omnipay\Common\CreditCard;
+use Omnipay\Common\Exception\InvalidRequestException;
 use Omnipay\PayPal\Message\ExpressInContextAuthorizeRequest;
 use Omnipay\PayPal\Support\InstantUpdateApi\ShippingOption;
 use Omnipay\Tests\TestCase;
@@ -14,7 +15,7 @@ class ExpressInContextAuthorizeRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
@@ -305,10 +306,8 @@ public function testDataWithCallbackAndNoDefaultShippingOption()
             'shippingOptions' => $shippingOptions,
         )));
 
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            'One of the supplied shipping options must be set as default'
-        );
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage('One of the supplied shipping options must be set as default');
 
         $this->request->getData();
     }
@@ -320,10 +319,8 @@ public function testNoAmount()
 
         $this->request->initialize($baseData);
 
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            'The amount parameter is required'
-        );
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage('The amount parameter is required');
 
         $this->request->getData();
     }
@@ -336,10 +333,8 @@ public function testAmountButNoReturnUrl()
 
         $this->request->initialize($baseData);
 
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            'The returnUrl parameter is required'
-        );
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage('The returnUrl parameter is required');
 
         $this->request->getData();
     }
@@ -367,7 +362,7 @@ public function testBadCallbackConfiguration()
         // from the docblock on this exception -
         // Thrown when a request is invalid or missing required fields.
         // callback has been set but no shipping options so expect one of these:
-        $this->setExpectedException('\Omnipay\Common\Exception\InvalidRequestException');
+        $this->expectException(InvalidRequestException::class);
 
         $this->request->getData();
     }
diff --git a/tests/Message/ExpressTransactionSearchRequestTest.php b/tests/Message/ExpressTransactionSearchRequestTest.php
index c0164b5..ec8191d 100644
--- a/tests/Message/ExpressTransactionSearchRequestTest.php
+++ b/tests/Message/ExpressTransactionSearchRequestTest.php
@@ -2,6 +2,7 @@
 
 namespace Omnipay\PayPal\Message;
 
+use Omnipay\Common\Exception\InvalidRequestException;
 use Omnipay\Tests\TestCase;
 
 class ExpressTransactionSearchRequestTest extends TestCase
@@ -11,7 +12,7 @@ class ExpressTransactionSearchRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
@@ -73,10 +74,8 @@ public function testWithoutStartDate()
     {
         $this->request->initialize(array());
 
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            'The startDate parameter is required'
-        );
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage('The startDate parameter is required');
 
         $this->request->getData();
     }
@@ -85,11 +84,9 @@ public function testAmountWithoutCurrency()
     {
         $this->request->setStartDate('2015-01-01');
         $this->request->setAmount(150.00);
-
-        $this->setExpectedException(
-            '\Omnipay\Common\Exception\InvalidRequestException',
-            'The currency parameter is required'
-        );
+        
+        $this->expectException(InvalidRequestException::class);
+        $this->expectExceptionMessage('The currency parameter is required');
 
         $this->request->getData();
     }
diff --git a/tests/Message/ExpressVoidRequestTest.php b/tests/Message/ExpressVoidRequestTest.php
index 91f8a05..2fc4130 100644
--- a/tests/Message/ExpressVoidRequestTest.php
+++ b/tests/Message/ExpressVoidRequestTest.php
@@ -12,7 +12,7 @@ class ExpressVoidRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
diff --git a/tests/Message/FetchTransactionRequestTest.php b/tests/Message/FetchTransactionRequestTest.php
index 8ac7873..642ed44 100644
--- a/tests/Message/FetchTransactionRequestTest.php
+++ b/tests/Message/FetchTransactionRequestTest.php
@@ -12,7 +12,7 @@ class FetchTransactionRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
 
diff --git a/tests/Message/ProAuthorizeRequestTest.php b/tests/Message/ProAuthorizeRequestTest.php
index 6e9af31..5767694 100644
--- a/tests/Message/ProAuthorizeRequestTest.php
+++ b/tests/Message/ProAuthorizeRequestTest.php
@@ -12,7 +12,7 @@ class ProAuthorizeRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
diff --git a/tests/Message/ProPurchaseRequestTest.php b/tests/Message/ProPurchaseRequestTest.php
index 9f88c10..d406a2d 100644
--- a/tests/Message/ProPurchaseRequestTest.php
+++ b/tests/Message/ProPurchaseRequestTest.php
@@ -12,7 +12,7 @@ class ProPurchaseRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
diff --git a/tests/Message/RefundRequestTest.php b/tests/Message/RefundRequestTest.php
index 036f6d2..4604b7d 100644
--- a/tests/Message/RefundRequestTest.php
+++ b/tests/Message/RefundRequestTest.php
@@ -12,7 +12,7 @@ class RefundRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
 
diff --git a/tests/Message/RestAuthorizeRequestTest.php b/tests/Message/RestAuthorizeRequestTest.php
index 5f0f962..89f1b56 100644
--- a/tests/Message/RestAuthorizeRequestTest.php
+++ b/tests/Message/RestAuthorizeRequestTest.php
@@ -12,7 +12,7 @@ class RestAuthorizeRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
diff --git a/tests/Message/RestAuthorizeResponseTest.php b/tests/Message/RestAuthorizeResponseTest.php
index 5e1bb20..b3bfee9 100644
--- a/tests/Message/RestAuthorizeResponseTest.php
+++ b/tests/Message/RestAuthorizeResponseTest.php
@@ -11,7 +11,9 @@ class RestAuthorizeResponseTest extends TestCase
     public function testRestPurchaseWithoutCardSuccess()
     {
         $httpResponse = $this->getMockHttpResponse('RestPurchaseWithoutCardSuccess.txt');
-        $response = new RestAuthorizeResponse($this->getMockRequest(), $httpResponse->json(), $httpResponse->getStatusCode());
+        $data = json_decode($httpResponse->getBody()->getContents(), true);
+
+        $response = new RestAuthorizeResponse($this->getMockRequest(), $data, $httpResponse->getStatusCode());
 
         $this->assertTrue($response->isSuccessful());
         $this->assertSame('PAY-3TJ47806DA028052TKTQGVYI', $response->getTransactionReference());
diff --git a/tests/Message/RestCancelSubscriptionRequestTest.php b/tests/Message/RestCancelSubscriptionRequestTest.php
index 7d6397d..4ebaa34 100644
--- a/tests/Message/RestCancelSubscriptionRequestTest.php
+++ b/tests/Message/RestCancelSubscriptionRequestTest.php
@@ -10,7 +10,7 @@ class RestCancelSubscriptionRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestCancelSubscriptionRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestCompletePurchaseRequestTest.php b/tests/Message/RestCompletePurchaseRequestTest.php
index 4dfbf98..bad9162 100644
--- a/tests/Message/RestCompletePurchaseRequestTest.php
+++ b/tests/Message/RestCompletePurchaseRequestTest.php
@@ -14,7 +14,7 @@ class RestCompletePurchaseRequestTest extends TestCase
     private $request;
 
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
diff --git a/tests/Message/RestCompleteSubscriptionRequestTest.php b/tests/Message/RestCompleteSubscriptionRequestTest.php
index 9c014f8..b72ac55 100644
--- a/tests/Message/RestCompleteSubscriptionRequestTest.php
+++ b/tests/Message/RestCompleteSubscriptionRequestTest.php
@@ -10,7 +10,7 @@ class RestCompleteSubscriptionRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestCompleteSubscriptionRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestCreateCardRequestTest.php b/tests/Message/RestCreateCardRequestTest.php
index 0574a0d..8e6d6df 100644
--- a/tests/Message/RestCreateCardRequestTest.php
+++ b/tests/Message/RestCreateCardRequestTest.php
@@ -13,7 +13,7 @@ class RestCreateCardRequestTest extends TestCase
     /** @var CreditCard */
     protected $card;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
diff --git a/tests/Message/RestCreatePlanRequestTest.php b/tests/Message/RestCreatePlanRequestTest.php
index b6a50b2..d1159cf 100644
--- a/tests/Message/RestCreatePlanRequestTest.php
+++ b/tests/Message/RestCreatePlanRequestTest.php
@@ -10,7 +10,7 @@ class RestCreatePlanRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestCreatePlanRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestCreateSubscriptionRequestTest.php b/tests/Message/RestCreateSubscriptionRequestTest.php
index 2ae9cd5..dc8e894 100644
--- a/tests/Message/RestCreateSubscriptionRequestTest.php
+++ b/tests/Message/RestCreateSubscriptionRequestTest.php
@@ -10,7 +10,7 @@ class RestCreateSubscriptionRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestCreateSubscriptionRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestCreateWebhookRequestTest.php b/tests/Message/RestCreateWebhookRequestTest.php
new file mode 100644
index 0000000..c4b92c2
--- /dev/null
+++ b/tests/Message/RestCreateWebhookRequestTest.php
@@ -0,0 +1,60 @@
+<?php
+
+namespace Omnipay\PayPal\Message;
+
+use Omnipay\Tests\TestCase;
+
+final class RestCreateWebhookRequestTest extends TestCase
+{
+    /**
+     * @var RestCreateWebhookRequest
+     */
+    private $request;
+
+    public function setUp() : void
+    {
+        $client = $this->getHttpClient();
+        $request = $this->getHttpRequest();
+        $this->request = new RestCreateWebhookRequest($client, $request);
+    }
+
+    public function testGetData()
+    {
+        $event1 = 'PAYMENT.AUTHORIZATION.CREATED';
+        $event2 = 'PAYMENT.AUTHORIZATION.VOIDED';
+        $url = 'https://foo.bar/baz';
+        $this->request->initialize(
+            [
+                'event_types' => [$event1, $event2],
+                'url' => $url,
+            ]
+        );
+
+        $this->assertEquals(
+            [
+                'event_types' => [['name' => $event1], ['name' => $event2]],
+                'url' => $url,
+            ],
+            $this->request->getData()
+        );
+    }
+
+    public function testGetEndpoint()
+    {
+        $this->assertStringEndsWith('/notifications/webhooks', $this->request->getEndpoint());
+    }
+
+    public function testGetEventTypes()
+    {
+        $value = ['PAYMENT.AUTHORIZATION.CREATED'];
+        $this->request->setEventTypes($value);
+        self::assertSame($value, $this->request->getEventTypes());
+    }
+
+    public function testGetUrl()
+    {
+        $value = 'https://foo.bar/baz';
+        $this->request->setUrl($value);
+        self::assertSame($value, $this->request->getUrl());
+    }
+}
diff --git a/tests/Message/RestDeleteCardRequestTest.php b/tests/Message/RestDeleteCardRequestTest.php
index e17620a..90cd68d 100644
--- a/tests/Message/RestDeleteCardRequestTest.php
+++ b/tests/Message/RestDeleteCardRequestTest.php
@@ -13,7 +13,7 @@ class RestDeleteCardRequestTest extends TestCase
     /** @var CreditCard */
     private $card;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
diff --git a/tests/Message/RestFetchPurchaseRequestTest.php b/tests/Message/RestFetchPurchaseRequestTest.php
index 8bf27d9..e4c8c55 100644
--- a/tests/Message/RestFetchPurchaseRequestTest.php
+++ b/tests/Message/RestFetchPurchaseRequestTest.php
@@ -9,7 +9,7 @@ class RestFetchPurchaseRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestFetchPurchaseRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestFetchTransactionRequestTest.php b/tests/Message/RestFetchTransactionRequestTest.php
index 9ba5a38..0623265 100644
--- a/tests/Message/RestFetchTransactionRequestTest.php
+++ b/tests/Message/RestFetchTransactionRequestTest.php
@@ -9,7 +9,7 @@ class RestFetchTransactionRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestFetchTransactionRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestListPlanRequestTest.php b/tests/Message/RestListPlanRequestTest.php
index ba1867e..4a99fef 100644
--- a/tests/Message/RestListPlanRequestTest.php
+++ b/tests/Message/RestListPlanRequestTest.php
@@ -9,7 +9,7 @@ class RestListPlanRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestListPlanRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestListWebhooksRequestTest.php b/tests/Message/RestListWebhooksRequestTest.php
new file mode 100644
index 0000000..e5e5d1f
--- /dev/null
+++ b/tests/Message/RestListWebhooksRequestTest.php
@@ -0,0 +1,30 @@
+<?php
+
+namespace Omnipay\PayPal\Message;
+
+use Omnipay\Tests\TestCase;
+
+final class RestListWebhooksRequestTest extends TestCase
+{
+    /**
+     * @var RestListWebhooksRequest
+     */
+    private $request;
+
+    public function setUp() : void
+    {
+        $client = $this->getHttpClient();
+        $request = $this->getHttpRequest();
+        $this->request = new RestListWebhooksRequest($client, $request);
+    }
+
+    public function testEndpoint()
+    {
+        $this->assertStringEndsWith('/notifications/webhooks', $this->request->getEndpoint());
+    }
+
+    public function testGetData()
+    {
+        $this->assertEmpty($this->request->getData());
+    }
+}
diff --git a/tests/Message/RestReactivateSubscriptionRequestTest.php b/tests/Message/RestReactivateSubscriptionRequestTest.php
index c8301f4..0f8571e 100644
--- a/tests/Message/RestReactivateSubscriptionRequestTest.php
+++ b/tests/Message/RestReactivateSubscriptionRequestTest.php
@@ -10,7 +10,7 @@ class RestReactivateSubscriptionRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestReactivateSubscriptionRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestResponseTest.php b/tests/Message/RestResponseTest.php
index c4e4d9d..ce852bb 100644
--- a/tests/Message/RestResponseTest.php
+++ b/tests/Message/RestResponseTest.php
@@ -9,7 +9,8 @@ class RestResponseTest extends TestCase
     public function testPurchaseSuccess()
     {
         $httpResponse = $this->getMockHttpResponse('RestPurchaseSuccess.txt');
-        $response = new RestResponse($this->getMockRequest(), $httpResponse->json(), $httpResponse->getStatusCode());
+        $data = json_decode($httpResponse->getBody()->getContents(), true);
+        $response = new RestResponse($this->getMockRequest(), $data, $httpResponse->getStatusCode());
 
         $this->assertTrue($response->isSuccessful());
         $this->assertSame('44E89981F8714392Y', $response->getTransactionReference());
@@ -19,7 +20,8 @@ public function testPurchaseSuccess()
     public function testPurchaseFailure()
     {
         $httpResponse = $this->getMockHttpResponse('RestPurchaseFailure.txt');
-        $response = new RestResponse($this->getMockRequest(), $httpResponse->json(), $httpResponse->getStatusCode());
+        $data = json_decode($httpResponse->getBody()->getContents(), true);
+        $response = new RestResponse($this->getMockRequest(), $data, $httpResponse->getStatusCode());
 
         $this->assertFalse($response->isSuccessful());
         $this->assertNull($response->getTransactionReference());
@@ -29,7 +31,9 @@ public function testPurchaseFailure()
     public function testCompletePurchaseSuccess()
     {
         $httpResponse = $this->getMockHttpResponse('RestCompletePurchaseSuccess.txt');
-        $response = new RestResponse($this->getMockRequest(), $httpResponse->json(), $httpResponse->getStatusCode());
+        $data = json_decode($httpResponse->getBody()->getContents(), true);
+
+        $response = new RestResponse($this->getMockRequest(), $data, $httpResponse->getStatusCode());
 
         $this->assertTrue($response->isSuccessful());
         $this->assertSame('9EA05739TH369572R', $response->getTransactionReference());
@@ -39,7 +43,9 @@ public function testCompletePurchaseSuccess()
     public function testCompletePurchaseFailure()
     {
         $httpResponse = $this->getMockHttpResponse('RestCompletePurchaseFailure.txt');
-        $response = new RestResponse($this->getMockRequest(), $httpResponse->json(), $httpResponse->getStatusCode());
+        $data = json_decode($httpResponse->getBody()->getContents(), true);
+
+        $response = new RestResponse($this->getMockRequest(), $data, $httpResponse->getStatusCode());
 
         $this->assertFalse($response->isSuccessful());
         $this->assertNull($response->getTransactionReference());
@@ -49,7 +55,9 @@ public function testCompletePurchaseFailure()
     public function testTokenFailure()
     {
         $httpResponse = $this->getMockHttpResponse('RestTokenFailure.txt');
-        $response = new RestResponse($this->getMockRequest(), $httpResponse->json(), $httpResponse->getStatusCode());
+        $data = json_decode($httpResponse->getBody()->getContents(), true);
+
+        $response = new RestResponse($this->getMockRequest(), $data, $httpResponse->getStatusCode());
 
         $this->assertFalse($response->isSuccessful());
         $this->assertSame('Client secret does not match for this client', $response->getMessage());
@@ -58,7 +66,9 @@ public function testTokenFailure()
     public function testAuthorizeSuccess()
     {
         $httpResponse = $this->getMockHttpResponse('RestAuthorizationSuccess.txt');
-        $response = new RestResponse($this->getMockRequest(), $httpResponse->json(), $httpResponse->getStatusCode());
+        $data = json_decode($httpResponse->getBody()->getContents(), true);
+
+        $response = new RestResponse($this->getMockRequest(), $data, $httpResponse->getStatusCode());
 
         $this->assertTrue($response->isSuccessful());
         $this->assertSame('58N7596879166930B', $response->getTransactionReference());
@@ -68,7 +78,9 @@ public function testAuthorizeSuccess()
     public function testCreateCardSuccess()
     {
         $httpResponse = $this->getMockHttpResponse('RestCreateCardSuccess.txt');
-        $response = new RestResponse($this->getMockRequest(), $httpResponse->json(), $httpResponse->getStatusCode());
+        $data = json_decode($httpResponse->getBody()->getContents(), true);
+
+        $response = new RestResponse($this->getMockRequest(), $data, $httpResponse->getStatusCode());
 
         $this->assertTrue($response->isSuccessful());
         $this->assertSame('CARD-70E78145XN686604FKO3L6OQ', $response->getCardReference());
diff --git a/tests/Message/RestSearchTransactionRequestTest.php b/tests/Message/RestSearchTransactionRequestTest.php
index e66b200..ab7ffd5 100644
--- a/tests/Message/RestSearchTransactionRequestTest.php
+++ b/tests/Message/RestSearchTransactionRequestTest.php
@@ -10,7 +10,7 @@ class RestSearchTransactionRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestSearchTransactionRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestSuspendSubscriptionRequestTest.php b/tests/Message/RestSuspendSubscriptionRequestTest.php
index 19d88fc..6cda5ed 100644
--- a/tests/Message/RestSuspendSubscriptionRequestTest.php
+++ b/tests/Message/RestSuspendSubscriptionRequestTest.php
@@ -10,7 +10,7 @@ class RestSuspendSubscriptionRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestSuspendSubscriptionRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestUpdatePlanRequestTest.php b/tests/Message/RestUpdatePlanRequestTest.php
index a682f15..1b12f6c 100644
--- a/tests/Message/RestUpdatePlanRequestTest.php
+++ b/tests/Message/RestUpdatePlanRequestTest.php
@@ -10,7 +10,7 @@ class RestUpdatePlanRequestTest extends TestCase
     /** @var \Omnipay\PayPal\Message\RestUpdatePlanRequest */
     private $request;
 
-    public function setUp()
+    public function setUp() : void
     {
         $client = $this->getHttpClient();
         $request = $this->getHttpRequest();
diff --git a/tests/Message/RestVerifyWebhookSignatureRequestTest.php b/tests/Message/RestVerifyWebhookSignatureRequestTest.php
new file mode 100644
index 0000000..b61b1d8
--- /dev/null
+++ b/tests/Message/RestVerifyWebhookSignatureRequestTest.php
@@ -0,0 +1,63 @@
+<?php
+
+namespace Omnipay\PayPal\Message;
+
+use Omnipay\Tests\TestCase;
+
+final class RestVerifyWebhookSignatureRequestTest extends TestCase
+{
+    /**
+     * @var RestVerifyWebhookSignatureRequest
+     */
+    private $request;
+
+    public function setUp() : void
+    {
+        $client = $this->getHttpClient();
+        $request = $this->getHttpRequest();
+        $this->request = new RestVerifyWebhookSignatureRequest($client, $request);
+    }
+
+    public function testGetData()
+    {
+        $data = [
+            'transmission_id' => 'foo',
+            'auth_algo' => 'bar',
+            'cert_url' => 'baz',
+            'transmission_sig' => 'qux',
+            'transmission_time' => 'foobar',
+            'webhook_event' => ['bar' => 'baz'],
+            'webhook_id' => 'barbaz',
+        ];
+
+        $this->request->initialize($data);
+
+        $this->assertEquals($data, $this->request->getData());
+    }
+
+    public function testGettersAndSetters() {
+        $authAlgo = 'foo';
+        $certUrl = 'bar';
+        $transmissionId = 'baz';
+        $transmissionTime = 'qux';
+        $transmissionSig = 'foobar';
+        $webhookEvent = ['bar' => 'baz'];
+        $webhookId = 'barfoo';
+
+        $this->request->setAuthAlgo($authAlgo);
+        $this->request->setCertUrl($certUrl);
+        $this->request->setTransmissionId($transmissionId);
+        $this->request->setTransmissionTime($transmissionTime);
+        $this->request->setTransmissionSig($transmissionSig);
+        $this->request->setWebhookEvent($webhookEvent);
+        $this->request->setWebhookId($webhookId);
+
+        $this->assertEquals($authAlgo, $this->request->getAuthAlgo());
+        $this->assertEquals($certUrl,$this->request->getCertUrl());
+        $this->assertEquals($transmissionId, $this->request->getTransmissionId());
+        $this->assertEquals($transmissionTime, $this->request->getTransmissionTime());
+        $this->assertEquals($transmissionSig, $this->request->getTransmissionSig());
+        $this->assertEquals($webhookEvent, $this->request->getWebhookEvent());
+        $this->assertEquals($webhookId, $this->request->getWebhookId());
+    }
+}
diff --git a/tests/Message/RestVerifyWebhookSignatureResponseTest.php b/tests/Message/RestVerifyWebhookSignatureResponseTest.php
new file mode 100644
index 0000000..a9a1e87
--- /dev/null
+++ b/tests/Message/RestVerifyWebhookSignatureResponseTest.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Omnipay\PayPal\Message;
+
+use Omnipay\Tests\TestCase;
+
+final class RestVerifyWebhookSignatureResponseTest extends TestCase
+{
+    public function testGetVerificationStatus()
+    {
+        $response = new RestVerifyWebhookSignatureResponse(
+            $this->getMockRequest(),
+            ['verification_status' => 'SUCCESS']
+        );
+
+        $this->assertSame('SUCCESS', $response->getVerificationStatus());
+    }
+
+    public function testIsSuccessfulWillReturnFalseIfParentCheckIsSuccesfullButVerificationFailed()
+    {
+        $response = new RestVerifyWebhookSignatureResponse(
+            $this->getMockRequest(),
+            ['verification_status' => 'FAILED']
+        );
+
+        $this->assertFalse($response->isSuccessful());
+    }
+
+    public function testIsSuccessfulWillReturnFalseIfParentCheckIsUnsuccesfull()
+    {
+        $response = new RestVerifyWebhookSignatureResponse(
+            $this->getMockRequest(),
+            ['verification_status' => 'foobar'],
+            400
+        );
+
+        $this->assertFalse($response->isSuccessful());
+    }
+
+    public function testIsSuccessfulWillReturnTrueIfEverythingIsOk()
+    {
+        $response = new RestVerifyWebhookSignatureResponse(
+            $this->getMockRequest(),
+            ['verification_status' => 'SUCCESS']
+        );
+
+        $this->assertTrue($response->isSuccessful());
+    }
+}
diff --git a/tests/Mock/RestGenericSubscriptionSuccess.txt b/tests/Mock/RestGenericSubscriptionSuccess.txt
index e099ab1..dc0ec05 100644
--- a/tests/Mock/RestGenericSubscriptionSuccess.txt
+++ b/tests/Mock/RestGenericSubscriptionSuccess.txt
@@ -5,3 +5,5 @@ Paypal-Debug-Id: 217a9ddefd384
 SERVER_INFO: identitysecuretokenserv:v1.oauth2.token&CalThreadId=91&TopLevelTxnStartTime=146fbfe679a&Host=slcsbidensectoken502.slc.paypal.com&pid=29059
 CORRELATION-ID: 217a9ddefd384
 Date: Thu, 03 Jul 2014 11:31:32 GMT
+
+{}
diff --git a/tests/ProGatewayTest.php b/tests/ProGatewayTest.php
index cdb05e2..76c7938 100644
--- a/tests/ProGatewayTest.php
+++ b/tests/ProGatewayTest.php
@@ -7,7 +7,7 @@
 
 class ProGatewayTest extends GatewayTestCase
 {
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
@@ -20,7 +20,7 @@ public function setUp()
                 'lastName' => 'User',
                 'number' => '4111111111111111',
                 'expiryMonth' => '12',
-                'expiryYear' => '2017',
+                'expiryYear' => date('Y'),
                 'cvv' => '123',
             )),
         );
diff --git a/tests/RestGatewayTest.php b/tests/RestGatewayTest.php
index db89871..9febb27 100644
--- a/tests/RestGatewayTest.php
+++ b/tests/RestGatewayTest.php
@@ -2,8 +2,11 @@
 
 namespace Omnipay\PayPal;
 
-use Omnipay\Tests\GatewayTestCase;
 use Omnipay\Common\CreditCard;
+use Omnipay\PayPal\Message\RestCreateWebhookRequest;
+use Omnipay\PayPal\Message\RestListWebhooksRequest;
+use Omnipay\PayPal\Message\RestVerifyWebhookSignatureRequest;
+use Omnipay\Tests\GatewayTestCase;
 
 class RestGatewayTest extends GatewayTestCase
 {
@@ -16,7 +19,7 @@ class RestGatewayTest extends GatewayTestCase
     /** @var array */
     public $subscription_options;
 
-    public function setUp()
+    public function setUp() : void
     {
         parent::setUp();
 
@@ -31,7 +34,7 @@ public function setUp()
                 'lastName' => 'User',
                 'number' => '4111111111111111',
                 'expiryMonth' => '12',
-                'expiryYear' => '2017',
+                'expiryYear' => date('Y'),
                 'cvv' => '123',
             )),
         );
@@ -218,6 +221,15 @@ public function testCreateCard()
         $this->assertNull($response->getMessage());
     }
 
+    public function testCreateWebhook()
+    {
+        $request = $this->gateway->createWebhook([]);
+
+        $this->assertInstanceOf(RestCreateWebhookRequest::class, $request);
+        $this->assertSame('https://api.paypal.com/v1/notifications/webhooks', $request->getEndpoint());
+        $this->assertEquals(['event_types' => [], 'url' => null], $request->getData());
+    }
+
     public function testPayWithSavedCard()
     {
         $this->setMockHttpResponse('RestCreateCardSuccess.txt');
@@ -277,7 +289,7 @@ public function testRefundCapture()
         $this->assertSame('abc123', $request->getTransactionReference());
         $endPoint = $request->getEndpoint();
         $this->assertSame('https://api.paypal.com/v1/payments/capture/abc123/refund', $endPoint);
-        
+
         $request->setAmount('15.99');
         $request->setCurrency('BRL');
         $request->setDescription('Test Description');
@@ -300,4 +312,33 @@ public function testVoid()
         $data = $request->getData();
         $this->assertEmpty($data);
     }
+
+    public function testListWebhooks()
+    {
+        $request = $this->gateway->listWebhooks([]);
+
+        $this->assertInstanceOf(RestListWebhooksRequest::class, $request);
+        $this->assertSame('https://api.paypal.com/v1/notifications/webhooks', $request->getEndpoint());
+        $this->assertEmpty($request->getData());
+    }
+
+    public function testVerifyWebhook()
+    {
+        $request = $this->gateway->verifyWebhookSignature([]);
+
+        $this->assertInstanceOf(RestVerifyWebhookSignatureRequest::class, $request);
+        $this->assertSame('https://api.paypal.com/v1/notifications/verify-webhook-signature', $request->getEndpoint());
+        $this->assertEquals(
+            [
+                'transmission_id' => null,
+                'auth_algo' => null,
+                'cert_url' => null,
+                'transmission_sig' => null,
+                'transmission_time' => null,
+                'webhook_event' => null,
+                'webhook_id' => null,
+            ],
+            $request->getData()
+        );
+    }
 }