diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 21dd30a..bb2016e 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-versions: ['7.3', '7.4']
+        php-versions: ['7.3', '7.4', '8.0']
 
     steps:
     - name: Install prerequesits
@@ -20,8 +20,8 @@ jobs:
         tools: composer
     - name: Install dependencies
       run: |
-        composer update 
+        composer update
         composer style
         composer install
     - name: Test
-      run: composer test
\ No newline at end of file
+      run: composer test
diff --git a/composer.json b/composer.json
index 0cdffd2..0cb4929 100644
--- a/composer.json
+++ b/composer.json
@@ -24,13 +24,13 @@
         }
     },
     "require": {
-        "php": ">=5.6",
+        "php": "^8.0",
         "emartech/escher": "1",
         "guzzlehttp/guzzle": "6",
         "psr/log": "1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^5.7",
+        "phpunit/phpunit": "^8.4",
         "squizlabs/php_codesniffer": "^3.3"
     },
     "suggest": {
diff --git a/tests/CachedClientTest.php b/tests/CachedClientTest.php
index aa273f1..111d183 100644
--- a/tests/CachedClientTest.php
+++ b/tests/CachedClientTest.php
@@ -2,6 +2,7 @@
 
 namespace Test\SessionValidator;
 
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use SessionValidator\Cache\CacheInterface;
 use SessionValidator\CachedClient;
@@ -9,24 +10,28 @@
 
 class CachedClientTest extends TestCase
 {
-    /** @var ClientInterface|\PHPUnit_Framework_MockObject_MockObject */
+    /** @var ClientInterface|MockObject */
     private $clientMock;
-    /** @var CacheInterface|\PHPUnit_Framework_MockObject_MockObject */
+
+    /** @var CacheInterface|MockObject */
     private $cacheMock;
 
     /** @var string */
     private $msid;
+
     /** @var string */
     private $value;
+
     /** @var array */
     private $msids;
+
     /** @var array */
     private $invalidMsids;
 
     /** @var CachedClient */
     private $client;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->clientMock = $this->createMock(ClientInterface::class);
         $this->cacheMock = $this->createMock(CacheInterface::class);
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index 1933e44..b7d791a 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -4,13 +4,14 @@
 
 use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\Psr7\Response;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use SessionValidator\Client;
 use SessionValidator\Http\EscherClient;
 
 class ClientTest extends TestCase
 {
-    /** @var EscherClient|\PHPUnit_Framework_MockObject_MockObject */
+    /** @var EscherClient|MockObject */
     private $escherClientMock;
 
     /** @var string */
@@ -19,7 +20,7 @@ class ClientTest extends TestCase
     /** @var Client */
     private $client;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->escherClientMock = $this->createMock(EscherClient::class);
 
@@ -89,7 +90,12 @@ public function filterInvalidCallsTheProperApiEndpoint()
         $msids = ['msid1', 'msid2'];
         $body = json_encode(['msids' => $msids]);
 
-        $this->expectHttpRequest('POST', "{$this->serviceUrl}/sessions/filter", $body);
+        $this->expectHttpRequest(
+            'POST',
+            "{$this->serviceUrl}/sessions/filter",
+            $body,
+            new Response(200, [], json_encode(['msids' => ['msid1']]))
+        );
 
         $this->client->filterInvalid($msids);
     }
@@ -153,8 +159,9 @@ private function mockHttpClientException()
             ->willThrowException(new TransferException());
     }
 
-    private function expectHttpRequest($method, $url, $body)
+    private function expectHttpRequest($method, $url, $body, $response = null)
     {
+        $responseReturned = $response ?? new Response();
         $this->escherClientMock
             ->expects($this->once())
             ->method('request')
@@ -162,6 +169,6 @@ private function expectHttpRequest($method, $url, $body)
                 'headers' => ['Content-Type' => 'application/json'],
                 'body' => $body
             ])
-            ->willReturn(new Response());
+            ->willReturn($responseReturned);
     }
 }
diff --git a/tests/Http/EscherClientTest.php b/tests/Http/EscherClientTest.php
index e118816..b55db8b 100644
--- a/tests/Http/EscherClientTest.php
+++ b/tests/Http/EscherClientTest.php
@@ -4,27 +4,31 @@
 
 use Escher\Escher;
 use GuzzleHttp\ClientInterface;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use SessionValidator\Http\EscherClient;
 
 class EscherClientTest extends TestCase
 {
-    /** @var ClientInterface|\PHPUnit_Framework_MockObject_MockObject */
+    /** @var ClientInterface|MockObject */
     private $clientMock;
-    /** @var Escher|\PHPUnit_Framework_MockObject_MockObject */
+
+    /** @var Escher|MockObject */
     private $escherMock;
 
     /** @var string */
     private $escherKey;
+
     /** @var string */
     private $escherSecret;
+
     /** @var array */
     private $requestOptions;
 
     /** @var EscherClient */
     private $client;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->clientMock = $this->createMock(ClientInterface::class);
         $this->escherMock = $this->createMock(Escher::class);