diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
new file mode 100644
index 00000000..1fa84fbd
--- /dev/null
+++ b/.github/workflows/run-tests.yml
@@ -0,0 +1,43 @@
+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: [8.0, 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
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 2fe44cdd..00000000
--- a/.travis.yml
+++ /dev/null
@@ -1,16 +0,0 @@
-language: php
-
-php:
-  - 5.6
-  - 7.0
-  - 7.1
-  - 7.2
-  - 7.3
-
-before_script:
-  - composer install -n --dev --prefer-source
-  - export XDEBUG_MODE=coverage
-
-script:
-  - vendor/bin/phpcs --standard=PSR2 src
-  - vendor/bin/phpunit --coverage-text
diff --git a/composer.json b/composer.json
index 40ebdeb5..89fe42d6 100644
--- a/composer.json
+++ b/composer.json
@@ -34,12 +34,13 @@
         }
     },
     "require": {
-        "php": "^5.6|^7",
+        "php": "^7.2|^8",
         "omnipay/common": "~3.0"
     },
     "require-dev": {
-        "omnipay/tests": "~3.0",
-        "squizlabs/php_codesniffer": "^3"
+        "omnipay/tests": "^4.1",
+        "squizlabs/php_codesniffer": "^3",
+        "phpspec/prophecy-phpunit": "^2.0"
     },
     "extra": {
         "branch-alias": {
diff --git a/tests/DirectGatewayTest.php b/tests/DirectGatewayTest.php
index 46858557..e37d3f26 100644
--- a/tests/DirectGatewayTest.php
+++ b/tests/DirectGatewayTest.php
@@ -6,7 +6,7 @@
 
 class DirectGatewayTest extends GatewayTestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/FormGatewayTest.php b/tests/FormGatewayTest.php
index 8f141b5d..4f3ad1a2 100644
--- a/tests/FormGatewayTest.php
+++ b/tests/FormGatewayTest.php
@@ -6,7 +6,7 @@
 
 class FormGatewayTest extends GatewayTestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
@@ -107,10 +107,10 @@ public function testPurchaseSuccess()
      * supplied, which largely amount to missing parameters.
      *
      * @dataProvider missingParameterProvider
-     * @expectedException \Omnipay\Common\Exception\InvalidRequestException
      */
     public function testAuthorizeFailure($missingParameter)
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidRequestException::class);
         $parameters = $this->purchaseOptions;
 
         unset($parameters[$missingParameter]);
@@ -180,37 +180,33 @@ public function testCompleteAuthorizeSuccess()
 
     /**
      * Invalid without any query parameter supplied.
-     * @expectedException Omnipay\Common\Exception\InvalidResponseException
      */
     public function testCompleteAuthorizeInvalid()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
         $response = $this->gateway->completeAuthorize($this->completePurchaseOptions)->send();
     }
 
     /**
      * Invalid without any query parameter supplied.
-     * @expectedException Omnipay\Common\Exception\InvalidResponseException
      */
     public function testCompletePurchaseInvalid1()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
         $response = $this->gateway->completePurchase($this->completePurchaseOptions)->send();
     }
 
-    /**
-     * @expectedException Omnipay\Common\Exception\InvalidResponseException
-     */
     public function testCompletePurchaseInvalid2()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
         // No leading '@'.
         $this->getHttpRequest()->initialize(['crypt' => 'ababab']);
         $response = $this->gateway->completePurchase($this->completePurchaseOptions)->send();
     }
 
-    /**
-     * @expectedException Omnipay\Common\Exception\InvalidResponseException
-     */
     public function testCompletePurchaseInvalid3()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
         // Not hexadecimal.
         $this->getHttpRequest()->initialize(['crypt' => '@ababxx']);
         $response = $this->gateway->completePurchase($this->completePurchaseOptions)->send();
@@ -275,11 +271,10 @@ public function testCompletePurchaseSuccess()
 
     /**
      * The wrong transaction ID is supplied with the server request.
-     *
-     * @expectedException Omnipay\Common\Exception\InvalidResponseException
      */
     public function testCompletePurchaseReplayAttack()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
         //$this->expectException(Complicated::class);
 
         // Set the "crypt" query parameter.
@@ -295,11 +290,10 @@ public function testCompletePurchaseReplayAttack()
 
     /**
      * The missing expected transaction ID supplied by the app.
-     *
-     * @expectedException Omnipay\Common\Exception\InvalidRequestException
      */
     public function testCompletePurchaseMissingExpectedParam()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidRequestException::class);
         //$this->expectException(Complicated::class);
 
         // Set the "crypt" query parameter.
diff --git a/tests/Message/DirectAuthorizeRequestTest.php b/tests/Message/DirectAuthorizeRequestTest.php
index e18bf2ba..736da121 100644
--- a/tests/Message/DirectAuthorizeRequestTest.php
+++ b/tests/Message/DirectAuthorizeRequestTest.php
@@ -16,7 +16,7 @@ class DirectAuthorizeRequestTest extends TestCase
      */
     protected $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
@@ -123,7 +123,7 @@ public function testBasket()
         // The element does exist, and must contain the basket XML, with optional XML header and
         // trailing newlines.
         $this->assertArrayHasKey('BasketXML', $data);
-        $this->assertContains($basketXml, $data['BasketXML']);
+        $this->assertStringContainsString($basketXml, $data['BasketXML']);
     }
 
     public function testBasketExtendItem()
@@ -151,7 +151,7 @@ public function testBasketExtendItem()
         // The element does exist, and must contain the basket XML, with optional XML header and
         // trailing newlines.
         $this->assertArrayHasKey('BasketXML', $data);
-        $this->assertContains($basketXml, $data['BasketXML']);
+        $this->assertStringContainsString($basketXml, $data['BasketXML']);
     }
 
     public function testGetDataNoReferrerId()
@@ -280,7 +280,7 @@ public function testBasketWithNoDiscount()
         // The element does exist, and must contain the basket XML, with optional XML header and
         // trailing newlines.
         $this->assertArrayHasKey('BasketXML', $data);
-        $this->assertNotContains('<discount>', $data['BasketXML']);
+        $this->assertStringNotContainsString('<discount>', $data['BasketXML']);
     }
 
     public function testMixedBasketWithSpecialChars()
@@ -321,7 +321,7 @@ public function testMixedBasketWithSpecialChars()
         $data = $this->request->getData();
 
         $this->assertArrayHasKey('BasketXML', $data);
-        $this->assertContains($expected, $data['BasketXML'], 'Basket XML does not match the expected output');
+        $this->assertStringContainsString($expected, $data['BasketXML'], 'Basket XML does not match the expected output');
     }
 
     public function testNonXmlBasket()
diff --git a/tests/Message/DirectPurchaseRequestTest.php b/tests/Message/DirectPurchaseRequestTest.php
index 1fb04176..6eb34b24 100644
--- a/tests/Message/DirectPurchaseRequestTest.php
+++ b/tests/Message/DirectPurchaseRequestTest.php
@@ -16,7 +16,7 @@ class DirectPurchaseRequestTest extends DirectAuthorizeRequestTest
      */
     protected $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/DirectTokenRequestTest.php b/tests/Message/DirectTokenRequestTest.php
index 3fb06dfa..9373615b 100644
--- a/tests/Message/DirectTokenRequestTest.php
+++ b/tests/Message/DirectTokenRequestTest.php
@@ -15,7 +15,7 @@ class DirectTokenRequestTest extends TestCase
      */
     protected $card;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->request = new DirectTokenRegistrationRequest(
             $this->getHttpClient(),
diff --git a/tests/Message/ResponseTest.php b/tests/Message/ResponseTest.php
index c993f8b9..6602250b 100644
--- a/tests/Message/ResponseTest.php
+++ b/tests/Message/ResponseTest.php
@@ -4,10 +4,13 @@
 
 use Omnipay\Common\Message\RequestInterface;
 use Omnipay\Tests\TestCase;
+use Prophecy\PhpUnit\ProphecyTrait;
 
 class ResponseTest extends TestCase
 {
-    public function setUp()
+    use ProphecyTrait;
+
+    public function setUp(): void
     {
         $this->getMockRequest()->shouldReceive('getTransactionId')->andReturn('123456');
     }
diff --git a/tests/Message/ServerAuthorizeRequestTest.php b/tests/Message/ServerAuthorizeRequestTest.php
index 4439b693..052ae0da 100644
--- a/tests/Message/ServerAuthorizeRequestTest.php
+++ b/tests/Message/ServerAuthorizeRequestTest.php
@@ -8,7 +8,7 @@ class ServerAuthorizeRequestTest extends TestCase
 {
     const SURCHARGE_XML = '<surcharges><surcharge><paymentType>VISA</paymentType><percentage>2.50</percentage></surcharge></surcharges>';
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/ServerAuthorizeResponseTest.php b/tests/Message/ServerAuthorizeResponseTest.php
index 50029e44..7e669b7d 100644
--- a/tests/Message/ServerAuthorizeResponseTest.php
+++ b/tests/Message/ServerAuthorizeResponseTest.php
@@ -6,7 +6,7 @@
 
 class ServerAuthorizeResponseTest extends TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $this->getMockRequest()->shouldReceive('getTransactionId')->andReturn('123456');
     }
diff --git a/tests/Message/ServerNotifyRequestTest.php b/tests/Message/ServerNotifyRequestTest.php
index 34dc9114..aa53b787 100644
--- a/tests/Message/ServerNotifyRequestTest.php
+++ b/tests/Message/ServerNotifyRequestTest.php
@@ -184,11 +184,10 @@ public function testError()
         $this->request->error('https://www.example.com/', 'detail');
     }
 
-    /**
-     * @expectedException \Omnipay\Common\Exception\InvalidResponseException
-     */
     public function testConfirmInvalidSignature()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
+
         $this->request = new ServerNotifyRequest(
             $this->getHttpClient(),
             $this->getHttpRequest()
@@ -200,11 +199,10 @@ public function testConfirmInvalidSignature()
         $this->request->confirm('https://www.example.com/', 'detail');
     }
 
-    /**
-     * @expectedException \Omnipay\Common\Exception\InvalidResponseException
-     */
     public function testErrorInvalidSignature()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
+
         $this->request = new ServerNotifyRequest(
             $this->getHttpClient(),
             $this->getHttpRequest()
diff --git a/tests/Message/ServerTokenRegistrationRequestTest.php b/tests/Message/ServerTokenRegistrationRequestTest.php
index 2668b8f0..4e6b51e3 100644
--- a/tests/Message/ServerTokenRegistrationRequestTest.php
+++ b/tests/Message/ServerTokenRegistrationRequestTest.php
@@ -12,7 +12,7 @@ class ServerTokenRegistrationRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/ServerTokenRegistrationResponseTest.php b/tests/Message/ServerTokenRegistrationResponseTest.php
index a40bfa59..d639b2b0 100644
--- a/tests/Message/ServerTokenRegistrationResponseTest.php
+++ b/tests/Message/ServerTokenRegistrationResponseTest.php
@@ -6,7 +6,7 @@
 
 class ServerTokenRegistrationResponseTest extends TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         $this->getMockRequest()->shouldReceive('getTransactionId')->andReturn('123456');
     }
diff --git a/tests/Message/SharedAbortRequestTest.php b/tests/Message/SharedAbortRequestTest.php
index 95dc5c55..e7519a36 100644
--- a/tests/Message/SharedAbortRequestTest.php
+++ b/tests/Message/SharedAbortRequestTest.php
@@ -6,7 +6,7 @@
 
 class SharedAbortRequestTest extends TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/SharedCaptureRequestTest.php b/tests/Message/SharedCaptureRequestTest.php
index ba73081b..3b33e3f7 100644
--- a/tests/Message/SharedCaptureRequestTest.php
+++ b/tests/Message/SharedCaptureRequestTest.php
@@ -6,7 +6,7 @@
 
 class SharedCaptureRequestTest extends TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
@@ -38,11 +38,10 @@ public function testTxType()
         $this->assertSame('RELEASE', $this->request->getTxType());
     }
 
-    /**
-     * @expectedException \Omnipay\Common\Exception\InvalidRequestException
-     */
     public function testMissingAmount()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidRequestException::class);
+
         $this->request->getData();
     }
 
@@ -60,22 +59,20 @@ public function testValid()
         $this->assertSame('4255', $data['TxAuthNo']);
     }
 
-    /**
-     * @expectedException \Omnipay\Common\Exception\InvalidRequestException
-     */
     public function testAuthMissingDescription()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidRequestException::class);
+
         $this->request->setAmount(123.45);
         $this->request->setUseAuthenticate(true);
 
         $this->request->getData();
     }
 
-    /**
-     * @expectedException \Omnipay\Common\Exception\InvalidRequestException
-     */
     public function testAuthMissingTransactionId()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidRequestException::class);
+
         $this->request->setAmount(123.45);
         $this->request->setDescription('desc');
         $this->request->setUseAuthenticate(true);
diff --git a/tests/Message/SharedRefundRequestTest.php b/tests/Message/SharedRefundRequestTest.php
index 320f5696..4054d831 100644
--- a/tests/Message/SharedRefundRequestTest.php
+++ b/tests/Message/SharedRefundRequestTest.php
@@ -6,7 +6,7 @@
 
 class SharedRefundRequestTest extends TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/SharedRepeatAuthorizeRequestTest.php b/tests/Message/SharedRepeatAuthorizeRequestTest.php
index a0a6e988..99257a00 100644
--- a/tests/Message/SharedRepeatAuthorizeRequestTest.php
+++ b/tests/Message/SharedRepeatAuthorizeRequestTest.php
@@ -11,7 +11,7 @@ class SharedRepeatAuthorizeRequestTest extends TestCase
      */
     protected $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/SharedRepeatPurchaseRequestTest.php b/tests/Message/SharedRepeatPurchaseRequestTest.php
index 166df08f..610bc453 100644
--- a/tests/Message/SharedRepeatPurchaseRequestTest.php
+++ b/tests/Message/SharedRepeatPurchaseRequestTest.php
@@ -11,7 +11,7 @@ class SharedRepeatPurchaseRequestTest extends TestCase
      */
     protected $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/Message/SharedTokenRemovalRequestTest.php b/tests/Message/SharedTokenRemovalRequestTest.php
index cf223023..62136f39 100644
--- a/tests/Message/SharedTokenRemovalRequestTest.php
+++ b/tests/Message/SharedTokenRemovalRequestTest.php
@@ -11,7 +11,7 @@ class SharedTokenRemovalRequestTest extends TestCase
      */
     private $request;
 
-    public function setUp()
+    public function setUp(): void
     {
         $this->request = new SharedTokenRemovalRequest($this->getHttpClient(), $this->getHttpRequest());
         $this->request->initialize(array(
diff --git a/tests/Message/SharedVoidRequestTest.php b/tests/Message/SharedVoidRequestTest.php
index 78f2b6d1..39804be1 100644
--- a/tests/Message/SharedVoidRequestTest.php
+++ b/tests/Message/SharedVoidRequestTest.php
@@ -6,7 +6,7 @@
 
 class SharedVoidRequestTest extends TestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
diff --git a/tests/ServerGatewayTest.php b/tests/ServerGatewayTest.php
index d7042801..91d23f35 100644
--- a/tests/ServerGatewayTest.php
+++ b/tests/ServerGatewayTest.php
@@ -8,7 +8,7 @@ class ServerGatewayTest extends GatewayTestCase
 {
     protected $error_3082_text = '3082 : The Description value is too long.';
 
-    public function setUp()
+    public function setUp(): void
     {
         parent::setUp();
 
@@ -129,11 +129,9 @@ public function testCompleteAuthorizeSuccess()
         $this->assertNull($response->getMessage());
     }
 
-    /**
-     * @expectedException Omnipay\Common\Exception\InvalidResponseException
-     */
     public function testCompleteAuthorizeInvalid()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
         $response = $this->gateway->completeAuthorize($this->completePurchaseOptions)->send();
     }
 
@@ -190,11 +188,9 @@ public function testCompletePurchaseSuccess()
         $this->assertNull($response->getMessage());
     }
 
-    /**
-     * @expectedException Omnipay\Common\Exception\InvalidResponseException
-     */
     public function testCompletePurchaseInvalid()
     {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
         $response = $this->gateway->completePurchase($this->completePurchaseOptions)->send();
     }