diff --git a/src/Message/PurchaseRequest.php b/src/Message/PurchaseRequest.php
index 51ddfcf..64283f1 100644
--- a/src/Message/PurchaseRequest.php
+++ b/src/Message/PurchaseRequest.php
@@ -23,7 +23,37 @@ public function getData()
         $data['type'] = $this->getType();
         $data['amount'] = $this->getAmount();
         $data['currency'] = $this->getCurrency();
-        $data['callbackUrls'] = [];
+
+        $data = array_merge($data, $this->getStoredCardData());
+        $data = array_merge($data, $this->getRecurringOptionsData());
+        $data = array_merge($data, $this->getMiscOptionsData());
+        $data = array_merge($data, $this->getCallbackUrlsData());
+
+        return $data;
+    }
+
+    public function sendData($data)
+    {
+        $headers = [
+            'Accept'        => 'application/json',
+            'Content-Type'  => 'application/json',
+            'Authorization' => 'Basic ' . $this->getAuthorization(),
+        ];
+
+        $httpResponse = $this->httpClient->request('POST', $this->getEndpoint('sessions'), $headers, json_encode($data));
+
+        try {
+            $responseData = json_decode($httpResponse->getBody()->getContents());
+        } catch (\Exception $exception) {
+            $responseData = [];
+        }
+
+        return $this->response = new PurchaseResponse($this, $responseData ?? []);
+    }
+
+    protected function getStoredCardData()
+    {
+        $data = [];
 
         if ( (bool) $this->getCreateToken() ) {
             $data['storeCard'] = true;
@@ -33,36 +63,38 @@ public function getData()
             $data['storedCardIndicator'] = $this->getStoredCardIndicator();
         }
 
-        if ( $this->getRecurringExpiry() ) {
-            $data['recurringExpiry'] = $this->getRecurringExpiry();
-        }
-
-        if ( $this->getRecurringFrequency() ) {
-            $data['recurringFrequency'] = $this->getRecurringFrequency();
-        }
-
         if ( $this->getToken() || $this->getCardReference() ) {
             $data['cardId'] = $this->getToken() ?? $this->getCardReference();
         }
 
-        if ( is_array($this->getPaymentMethods()) ) {
-            $data['methods'] = $this->getPaymentMethods();
-        }
-
         if ( is_array($this->getCardTypes()) ) {
             $data['cardTypes'] = $this->getCardTypes();
         }
 
-        if ( is_array($this->getMetadata()) ) {
-            $data['metaData'] = $this->getMetadata();
-        }
+        return $data;
+    }
 
-        $merchantReference = $this->getMerchantReference() ?? $this->getDescription();
+    protected function getRecurringOptionsData()
+    {
+        $data = [];
 
-        if ( $merchantReference ) {
-            $data['merchantReference'] = $merchantReference;
+        if ( $this->getRecurringExpiry() ) {
+            $data['recurringExpiry'] = $this->getRecurringExpiry();
+        }
+
+        if ( $this->getRecurringFrequency() ) {
+            $data['recurringFrequency'] = $this->getRecurringFrequency();
         }
 
+        return $data;
+    }
+
+    protected function getCallbackUrlsData()
+    {
+        $data = [
+            'callbackUrls' => []
+        ];
+
         if ( $this->getReturnUrl() ) {
             $data['callbackUrls']['approved'] = $this->getReturnUrl();
         }
@@ -82,22 +114,24 @@ public function getData()
         return $data;
     }
 
-    public function sendData($data)
+    protected function getMiscOptionsData()
     {
-        $headers = [
-            'Accept'        => 'application/json',
-            'Content-Type'  => 'application/json',
-            'Authorization' => 'Basic ' . $this->getAuthorization(),
-        ];
+        $data = [];
 
-        $httpResponse = $this->httpClient->request('POST', $this->getEndpoint('sessions'), $headers, json_encode($data));
+        if ( is_array($this->getPaymentMethods()) ) {
+            $data['methods'] = $this->getPaymentMethods();
+        }
 
-        try {
-            $responseData = json_decode($httpResponse->getBody()->getContents());
-        } catch (\Exception $exception) {
-            $responseData = [];
+        if ( is_array($this->getMetadata()) ) {
+            $data['metaData'] = $this->getMetadata();
         }
 
-        return $this->response = new PurchaseResponse($this, $responseData ?? []);
+        $merchantReference = $this->getMerchantReference() ?? $this->getDescription();
+
+        if ( $merchantReference ) {
+            $data['merchantReference'] = $merchantReference;
+        }
+
+        return $data;
     }
 }
diff --git a/tests/GatewayTest.php b/tests/GatewayTest.php
index 3dc7d8f..c408ad6 100644
--- a/tests/GatewayTest.php
+++ b/tests/GatewayTest.php
@@ -3,6 +3,7 @@
 namespace Omnipay\WindcaveHpp;
 
 use Omnipay\Tests\GatewayTestCase;
+use Omnipay\Common\Message\NotificationInterface;
 
 class GatewayTest extends GatewayTestCase
 {
@@ -16,15 +17,128 @@ public function setUp(): void
         $this->gateway = new Gateway($this->getHttpClient(), $this->getHttpRequest());
 
         $this->options = [
+            'apiUsername'   => 'merchant',
+            'apiKey'        => 'apikey',
             'amount'        => '1.45',
-            'apiUsername'   => 'Test_Merchant',
-            'apiKey'        => 'ABCDEF1234567890ABCDEF1234567890ABCDEF1234567890ABCDEF1234567890',
             'currency'      => 'NZD',
             'cancelUrl'     => 'https://www.example.com/cancel',
             'notifyUrl'     => 'https://www.example.com/notify',
             'returnUrl'     => 'https://www.example.com/return',
-            'transactionId' => '123abc',
+            'transactionId' => 'transaction123',
             'testMode'      => true,
+            'description'   => 'Test Transaction',
+            'type'          => 'purchase'
         ];
     }
+
+    public function testPurchaseSuccess()
+    {
+        $this->setMockHttpResponse('PurchaseSuccess.txt');
+
+        $request  = $this->gateway->purchase($this->options);
+        $response = $request->send();
+
+        $this->assertFalse($response->isSuccessful());
+        $this->assertTrue($response->isRedirect());
+        $this->assertSame('GET', $response->getRedirectMethod());
+        $this->assertSame('https://uat.windcave.com/pxmi3/session1234', $response->getRedirectUrl());
+        $this->assertSame([], $response->getRedirectData());
+    }
+
+    public function testCompletePurchaseSuccess()
+    {
+        $this->setMockHttpResponse('CompletePurchaseSuccess.txt');
+
+        $request = $this->gateway->completePurchase([
+            'apiUsername' => $this->options['apiUsername'],
+            'apiKey'      => $this->options['apiKey'],
+            'sessionId'   => 'session123',
+            'testMode'    => true,
+        ]);
+
+        $this->getHttpRequest()->request->set('sessionId','session123');
+
+        $response = $request->send();
+
+        $this->assertTrue($response->isSuccessful());
+        $this->assertSame('APPROVED', $response->getResponseText());
+        $this->assertSame('session123', $response->getSessionId());
+        $this->assertSame('merchantRef123', $response->getTransactionId());
+        $this->assertSame('transaction123', $response->getTransactionReference());
+        $this->assertSame('411111......1111', $response->getCard()['cardNumber']);
+    }
+
+    public function testAcceptNotificationPaid()
+    {
+        $this->setMockHttpResponse('CompletePurchaseSuccess.txt');
+
+        $this->getHttpRequest()->request->set('sessionId','session123');
+
+        $notification = $this->gateway->acceptNotification([
+            'apiUsername' => $this->options['apiUsername'],
+            'apiKey'      => $this->options['apiKey'],
+            'sessionId'   => 'session123',
+            'testMode'    => true,
+        ]);
+
+        $this->assertSame(NotificationInterface::STATUS_COMPLETED, $notification->getTransactionStatus());
+        $this->assertSame('transaction123', $notification->getTransactionReference());
+    }
+
+
+    public function testAcceptNotificationFailed()
+    {
+        $this->setMockHttpResponse('CompletePurchaseFailed.txt');
+
+        $this->getHttpRequest()->request->set('sessionId','session123');
+
+        $notification = $this->gateway->acceptNotification([
+            'apiUsername' => $this->options['apiUsername'],
+            'apiKey'      => $this->options['apiKey'],
+            'sessionId'   => 'SESSION123',
+            'testMode'    => true,
+        ]);
+
+        $this->assertSame(NotificationInterface::STATUS_FAILED, $notification->getTransactionStatus());
+    }
+
+    public function testRefundSuccess()
+    {
+        $this->setMockHttpResponse('RefundSuccess.txt');
+
+        $request = $this->gateway->refund([
+            'apiUsername'          => $this->options['apiUsername'],
+            'apiKey'               => $this->options['apiKey'],
+            'amount'               => '1.00',
+            'currency'             => 'GBP',
+            'transactionReference' => 'refundtransaction123',
+            'testMode'             => true,
+        ]);
+
+        $response = $request->send();
+
+        $this->assertTrue($response->isSuccessful());
+        $this->assertSame('refundtransaction123', $response->getTransactionReference());
+        $this->assertSame('APPROVED', $response->getMessage());
+    }
+
+    public function testRefundFailed()
+    {
+        $this->setMockHttpResponse('RefundFailed.txt');
+
+        $request = $this->gateway->refund([
+            'apiUsername'          => $this->options['apiUsername'],
+            'apiKey'               => $this->options['apiKey'],
+            'amount'               => '1.00',
+            'currency'             => 'GBP',
+            'transactionReference' => 'refundtransaction123',
+            'testMode'             => true,
+        ]);
+
+        $response = $request->send();
+
+        $this->assertFalse($response->isSuccessful());
+        $this->assertSame('refundtransaction123', $response->getTransactionReference());
+        $this->assertSame('DECLINED', $response->getMessage());
+    }
 }
diff --git a/tests/Message/PurchaseRequestTest.php b/tests/Message/PurchaseRequestTest.php
new file mode 100644
index 0000000..9a720d6
--- /dev/null
+++ b/tests/Message/PurchaseRequestTest.php
@@ -0,0 +1,126 @@
+<?php
+
+namespace Omnipay\WindcaveHpp\Message;
+
+use Omnipay\Tests\TestCase;
+
+class PurchaseRequestTest extends TestCase
+{
+    /** @var PurchaseRequest */
+    private $request;
+
+    public function setUp(): void
+    {
+        $this->options = [
+            'apiUsername'   => 'merchant',
+            'apiKey'        => 'apikey',
+            'amount'        => '1.45',
+            'currency'      => 'NZD',
+            'returnUrl'     => 'https://example.com/return',
+            'cancelUrl'     => 'https://example.com/cancel',
+            'notifyUrl'     => 'https://example.com/notify',
+            'transactionId' => 'transaction123',
+            'testMode'      => true,
+        ];
+
+        $this->request = new PurchaseRequest($this->getHttpClient(), $this->getHttpRequest());
+        $this->request->initialize($this->options);
+    }
+
+    public function testApiKeys(): void
+    {
+        $this->request->setApiUsername('user123');
+        $this->request->setApiKey('key123');
+
+        $this->assertSame('user123', $this->request->getApiUsername());
+        $this->assertSame('key123', $this->request->getApiKey());
+    }
+
+    public function testRequiredParameters(): void
+    {
+        $data = $this->request->getData();
+
+        $this->assertArrayHasKey('amount', $data);
+        $this->assertArrayHasKey('currency', $data);
+    }
+
+    public function testRedirect(): void
+    {
+        $this->setMockHttpResponse('PurchaseSuccess.txt');
+
+        $response = $this->request->send();
+
+        $this->assertFalse($response->isSuccessful());
+        $this->assertTrue($response->isRedirect());
+        $this->assertSame('GET', $response->getRedirectMethod());
+        $this->assertSame('https://uat.windcave.com/pxmi3/session1234', $response->getRedirectUrl());
+        $this->assertSame([], $response->getRedirectData());
+    }
+
+    public function testReturnUrls(): void
+    {
+        $this->request->setReturnUrl('https://example.com/return');
+        $this->request->setDeclineUrl('https://example.com/decline');
+        $this->request->setCancelUrl('https://example.com/cancel');
+        $this->request->setNotifyUrl('https://example.com/notify');
+
+        $data = $this->request->getData();
+
+        $this->assertSame('https://example.com/return', $data['callbackUrls']['approved']);
+        $this->assertSame('https://example.com/decline', $data['callbackUrls']['declined']);
+        $this->assertSame('https://example.com/cancel', $data['callbackUrls']['cancelled']);
+        $this->assertSame('https://example.com/notify', $data['notificationUrl']);
+    }
+
+    public function testCreateTokenSetsStoreCardTrue(): void
+    {
+        $this->request->setCreateToken(true);
+        $data = $this->request->getData();
+        $this->assertArrayHasKey('storeCard', $data);
+        $this->assertTrue($data['storeCard']);
+    }
+
+    public function testStoredCardIndicator(): void
+    {
+        $this->request->setStoredCardIndicator('credentialonfileinitial');
+        $data = $this->request->getData();
+        $this->assertSame('credentialonfileinitial', $data['storedCardIndicator']);
+    }
+
+    public function testRecurringFields(): void
+    {
+        $this->request->setRecurringFrequency('monthly');
+        $this->request->setRecurringExpiry('9999-12-31');
+        $data = $this->request->getData();
+        $this->assertSame('monthly', $data['recurringFrequency']);
+        $this->assertSame('9999-12-31', $data['recurringExpiry']);
+    }
+
+    public function testCardIdFromToken(): void
+    {
+        $this->request->setToken('tok_abc');
+        $data = $this->request->getData();
+        $this->assertSame('tok_abc', $data['cardId']);
+    }
+
+    public function testCardIdFromCardReference(): void
+    {
+        $this->request->setToken(null);
+        $this->request->setCardReference('card_ref_123');
+        $data = $this->request->getData();
+        $this->assertSame('card_ref_123', $data['cardId']);
+    }
+
+    public function testPaymentMethodsAndCardTypesAndMetadata(): void
+    {
+        $this->request->setPaymentMethods(['card', 'alipay']);
+        $this->request->setCardTypes(['visa', 'mastercard']);
+        $this->request->setMetadata(['key' => 'value']);
+
+        $data = $this->request->getData();
+
+        $this->assertSame(['card', 'alipay'], $data['methods']);
+        $this->assertSame(['visa', 'mastercard'], $data['cardTypes']);
+        $this->assertSame(['key' => 'value'], $data['metaData']);
+    }
+}
\ No newline at end of file
diff --git a/tests/Message/PurchaseResponseTest.php b/tests/Message/PurchaseResponseTest.php
new file mode 100644
index 0000000..addf66f
--- /dev/null
+++ b/tests/Message/PurchaseResponseTest.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Omnipay\WindcaveHpp\Message;
+
+use Omnipay\Tests\TestCase;
+use Omnipay\Common\Message\RequestInterface;
+
+class PurchaseResponseTest extends TestCase
+{
+    public function testGetRedirectUrlFindsHppLink(): void
+    {
+        $response = new PurchaseResponse($this->getMockRequest(), (object) [
+            'links' => [
+                (object) ['rel' => 'self', 'href' => 'https://uat.windcave.com/api/v1/sessions/session1234', 'method' => 'GET'],
+                (object) ['rel' => 'hpp',  'href' => 'https://uat.windcave.com/pxmi3/session1234', 'method' => 'REDIRECT'],
+                (object) ['rel' => 'hpp',  'href' => 'https://uat.windcave.com/api/v1/sessions/session1234', 'method' => 'PATCH'],
+            ],
+        ]);
+
+        $this->assertTrue($response->isRedirect());
+        $this->assertSame('GET', $response->getRedirectMethod());
+        $this->assertSame(
+            'https://uat.windcave.com/pxmi3/session1234',
+            $response->getRedirectUrl()
+        );
+    }
+
+    public function testGetRedirectUrlThrowsWhenMissing(): void
+    {
+        $this->expectException(\Omnipay\Common\Exception\InvalidResponseException::class);
+
+        $resp = new PurchaseResponse($this->getMockRequest(), (object) ['links' => [(object) ['rel' => 'self', 'href' => 'x']]]);
+
+        $resp->getRedirectUrl();
+    }
+}
\ No newline at end of file
diff --git a/tests/Message/RefundRequestTest.php b/tests/Message/RefundRequestTest.php
new file mode 100644
index 0000000..6cb4988
--- /dev/null
+++ b/tests/Message/RefundRequestTest.php
@@ -0,0 +1,63 @@
+<?php
+
+namespace Omnipay\WindcaveHpp\Message;
+use Omnipay\WindcaveHpp\Gateway;
+use Omnipay\Tests\TestCase;
+
+class RefundRequestTest extends TestCase
+{
+    protected $request;
+    protected $gateway;
+
+    protected function setUp(): void
+    {
+        $this->options = [
+            'apiUsername'   => 'merchant',
+            'apiKey'        => 'apikey',
+            'amount'        => '1.45',
+            'currency'      => 'NZD',
+        ];
+
+        $this->request = new RefundRequest($this->getHttpClient(), $this->getHttpRequest());
+        $this->request->initialize($this->options);
+        $this->gateway = new Gateway($this->getHttpClient(), $this->getHttpRequest());
+    }
+
+    public function testApiKeys(): void
+    {
+        $this->request->setApiUsername('user123');
+        $this->request->setApiKey('key123');
+
+        $this->assertSame('user123', $this->request->getApiUsername());
+        $this->assertSame('key123', $this->request->getApiKey());
+    }
+
+    public function testRequiredParameters(): void
+    {
+        $this->expectException(\Omnipay\Common\Exception\InvalidRequestException::class);
+        $data = $this->request->getData();
+
+        $this->assertArrayHasKey('amount', $data);
+        $this->assertArrayHasKey('currency', $data);
+    }
+
+    public function testRefundSuccess(): void
+    {
+        $this->setMockHttpResponse('RefundSuccess.txt');
+
+        $request = $this->gateway->refund([
+            'apiUsername'          => 'merchant',
+            'apiKey'               => 'apikey',
+            'amount'               => '1.45',
+            'currency'             => 'NZD',
+            'transactionReference' => 'refundtransaction123',
+            'testMode'             => true,
+        ]);
+
+        $response = $request->send();
+
+        $this->assertTrue($response->isSuccessful());
+        $this->assertSame('refundtransaction123', $response->getTransactionReference());
+        $this->assertSame('APPROVED', $response->getMessage());
+    }
+}
\ No newline at end of file
diff --git a/tests/Message/RefundResponseTest.php b/tests/Message/RefundResponseTest.php
new file mode 100644
index 0000000..a0653bb
--- /dev/null
+++ b/tests/Message/RefundResponseTest.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Omnipay\WindcaveHpp\Message;
+
+use Omnipay\Tests\TestCase;
+
+class RefundResponseTest extends TestCase
+{
+    public function testRefundSuccess()
+    {
+        $response = new RefundResponse($this->getMockRequest(), (object) [
+            'id' => 'refundtransaction123',
+            'type' => 'refund',
+            'responseText' => 'APPROVED',
+            'authorised' => true
+        ]);
+
+        $this->assertTrue($response->isSuccessful());
+        $this->assertSame('refundtransaction123', $response->getTransactionReference());
+        $this->assertSame('APPROVED', $response->getMessage());
+    }
+
+    public function testRefundFailure()
+    {
+        $response = new RefundResponse($this->getMockRequest(), (object) [
+            'id' => 'refundtransaction123',
+            'type' => 'refund',
+            'responseText' => 'DECLINED',
+            'authorised' => true
+        ]);
+
+        $this->assertFalse($response->isSuccessful());
+        $this->assertSame('refundtransaction123', $response->getTransactionReference());
+        $this->assertSame('DECLINED', $response->getMessage());
+    }
+}
\ No newline at end of file
diff --git a/tests/Mock/CompletePurchaseFailed.txt b/tests/Mock/CompletePurchaseFailed.txt
new file mode 100644
index 0000000..3e3d4fe
--- /dev/null
+++ b/tests/Mock/CompletePurchaseFailed.txt
@@ -0,0 +1,108 @@
+HTTP/1.1 200 OK
+Date: Thu, 01 May 2025 01:43:28 GMT
+Content-Type: application/json; charset=utf-8
+
+{
+  "id": "session123",
+  "state": "complete",
+  "type": "purchase",
+  "amount": "20.00",
+  "currency": "GBP",
+  "currencyNumeric": 826,
+  "merchantReference": "merchantRef1234",
+  "methods": [
+    "card",
+    "paypal",
+    "applepay",
+    "googlepay",
+    "klarna"
+  ],
+  "expires": "2025-08-20T21:45:26Z",
+  "callbackUrls": {
+    "approved": "http://www.example.com/return",
+    "declined": "http://www.example.com/decline",
+    "cancelled": "http://www.example.com/cancel"
+  },
+  "notificationUrl": "http://www.example.com/notify",
+  "storeCard": false,
+  "clientType": "internet",
+  "links": [
+    {
+      "href": "https://uat.windcave.com/api/v1/sessions/session123",
+      "rel": "self",
+      "method": "GET"
+    },
+    {
+      "href": "https://uat.windcave.com/api/v1/transactions/transaction123",
+      "rel": "transaction",
+      "method": "GET"
+    }
+  ],
+  "transactions": [
+    {
+      "id": "transaction123",
+      "username": "merchant",
+      "authorised": true,
+      "allowRetry": false,
+      "retryIndicator": "",
+      "reCo": "00",
+      "responseText": "FAILED",
+      "authCode": "019533",
+      "acquirer": {
+        "name": "Undefined",
+        "mid": "10000000",
+        "tid": "10001548",
+        "reCo": "00",
+        "responseText": "FAILED"
+      },
+      "type": "purchase",
+      "method": "card",
+      "localTimeZone": "UK_GMT",
+      "dateTimeUtc": "2025-08-17T22:06:51Z",
+      "dateTimeLocal": "2025-08-17T23:06:51+01:00",
+      "settlementDate": "2025-08-18",
+      "amount": "20.00",
+      "balanceAmount": "0.00",
+      "currency": "GBP",
+      "currencyNumeric": 826,
+      "clientType": "internet",
+      "merchantReference": "merchantRef123",
+      "card": {
+        "cardNumber2": "1111111111111111",
+        "cardHolderName": "WHPP",
+        "cardNumber": "411111......1111",
+        "dateExpiryMonth": "05",
+        "dateExpiryYear": "28",
+        "type": "visa"
+      },
+      "cvc2ResultCode": "U",
+      "storedCardIndicator": "single",
+      "notificationUrl": "http://www.example.com/notify",
+      "sessionId": "session123",
+      "browser": {
+        "ipAddress": "192.168.1.1",
+        "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36"
+      },
+      "isSurcharge": false,
+      "amountTotal": "20.00",
+      "liabilityIndicator": "standard",
+      "links": [
+        {
+          "href": "https://uat.windcave.com/api/v1/transactions/transaction123",
+          "rel": "self",
+          "method": "GET"
+        },
+        {
+          "href": "https://uat.windcave.com/api/v1/sessions/session123",
+          "rel": "session",
+          "method": "GET"
+        },
+        {
+          "href": "https://uat.windcave.com/api/v1/transactions",
+          "rel": "refund",
+          "method": "POST"
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/tests/Mock/CompletePurchaseSuccess.txt b/tests/Mock/CompletePurchaseSuccess.txt
new file mode 100644
index 0000000..bc56d96
--- /dev/null
+++ b/tests/Mock/CompletePurchaseSuccess.txt
@@ -0,0 +1,108 @@
+HTTP/1.1 200 OK
+Date: Thu, 01 May 2025 01:43:28 GMT
+Content-Type: application/json; charset=utf-8
+
+{
+  "id": "session123",
+  "state": "complete",
+  "type": "purchase",
+  "amount": "20.00",
+  "currency": "GBP",
+  "currencyNumeric": 826,
+  "merchantReference": "merchantRef1234",
+  "methods": [
+    "card",
+    "paypal",
+    "applepay",
+    "googlepay",
+    "klarna"
+  ],
+  "expires": "2025-08-20T21:45:26Z",
+  "callbackUrls": {
+    "approved": "http://www.example.com/return",
+    "declined": "http://www.example.com/decline",
+    "cancelled": "http://www.example.com/cancel"
+  },
+  "notificationUrl": "http://www.example.com/notify",
+  "storeCard": false,
+  "clientType": "internet",
+  "links": [
+    {
+      "href": "https://uat.windcave.com/api/v1/sessions/session123",
+      "rel": "self",
+      "method": "GET"
+    },
+    {
+      "href": "https://uat.windcave.com/api/v1/transactions/transaction123",
+      "rel": "transaction",
+      "method": "GET"
+    }
+  ],
+  "transactions": [
+    {
+      "id": "transaction123",
+      "username": "merchant",
+      "authorised": true,
+      "allowRetry": false,
+      "retryIndicator": "",
+      "reCo": "00",
+      "responseText": "APPROVED",
+      "authCode": "019533",
+      "acquirer": {
+        "name": "Undefined",
+        "mid": "10000000",
+        "tid": "10001548",
+        "reCo": "00",
+        "responseText": "APPROVED"
+      },
+      "type": "purchase",
+      "method": "card",
+      "localTimeZone": "UK_GMT",
+      "dateTimeUtc": "2025-08-17T22:06:51Z",
+      "dateTimeLocal": "2025-08-17T23:06:51+01:00",
+      "settlementDate": "2025-08-18",
+      "amount": "20.00",
+      "balanceAmount": "0.00",
+      "currency": "GBP",
+      "currencyNumeric": 826,
+      "clientType": "internet",
+      "merchantReference": "merchantRef123",
+      "card": {
+        "cardNumber2": "1111111111111111",
+        "cardHolderName": "WHPP",
+        "cardNumber": "411111......1111",
+        "dateExpiryMonth": "05",
+        "dateExpiryYear": "28",
+        "type": "visa"
+      },
+      "cvc2ResultCode": "U",
+      "storedCardIndicator": "single",
+      "notificationUrl": "http://www.example.com/notify",
+      "sessionId": "session123",
+      "browser": {
+        "ipAddress": "192.168.1.1",
+        "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36"
+      },
+      "isSurcharge": false,
+      "amountTotal": "20.00",
+      "liabilityIndicator": "standard",
+      "links": [
+        {
+          "href": "https://uat.windcave.com/api/v1/transactions/transaction123",
+          "rel": "self",
+          "method": "GET"
+        },
+        {
+          "href": "https://uat.windcave.com/api/v1/sessions/session123",
+          "rel": "session",
+          "method": "GET"
+        },
+        {
+          "href": "https://uat.windcave.com/api/v1/transactions",
+          "rel": "refund",
+          "method": "POST"
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/tests/Mock/PurchaseSuccess.txt b/tests/Mock/PurchaseSuccess.txt
new file mode 100644
index 0000000..5e1d4b4
--- /dev/null
+++ b/tests/Mock/PurchaseSuccess.txt
@@ -0,0 +1,25 @@
+HTTP/1.1 200 OK
+Date: Thu, 01 May 2025 01:43:28 GMT
+Content-Type: application/json; charset=utf-8
+
+{
+  "id": "000003000808885103d0e8240fe03294",
+  "state": "init",
+  "links": [
+    {
+      "href": "https://uat.windcave.com/api/v1/sessions/session1234",
+      "rel": "self",
+      "method": "GET"
+    },
+    {
+      "href": "https://uat.windcave.com/pxmi3/session1234",
+      "rel": "hpp",
+      "method": "REDIRECT"
+    },
+    {
+      "href": "https://uat.windcave.com/api/v1/sessions/session1234",
+      "rel": "cancel",
+      "method": "PATCH"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/tests/Mock/RefundFailed.txt b/tests/Mock/RefundFailed.txt
new file mode 100644
index 0000000..eea1ac0
--- /dev/null
+++ b/tests/Mock/RefundFailed.txt
@@ -0,0 +1,55 @@
+HTTP/1.1 200 OK
+Date: Thu, 01 May 2025 01:43:28 GMT
+Content-Type: application/json; charset=utf-8
+
+{
+  "id": "refundtransaction123",
+  "username": "merchant",
+  "authorised": true,
+  "allowRetry": false,
+  "retryIndicator": "",
+  "reCo": "00",
+  "responseText": "DECLINED",
+  "authCode": "001412",
+  "acquirer": {
+    "name": "Undefined",
+    "reCo": "",
+    "responseText": ""
+  },
+  "type": "refund",
+  "method": "card",
+  "localTimeZone": "UK_GMT",
+  "dateTimeUtc": "2025-08-19T01:34:55Z",
+  "dateTimeLocal": "2025-08-19T02:34:55+01:00",
+  "settlementDate": "2025-08-19",
+  "amount": "1.00",
+  "balanceAmount": "0.00",
+  "currency": "GBP",
+  "currencyNumeric": 826,
+  "clientType": "internet",
+  "merchantReference": "test1755567267ref",
+  "card": {
+    "cardNumber2": "9310200000000010",
+    "cardHolderName": "WHPP",
+    "cardNumber": "411111......1111",
+    "dateExpiryMonth": "02",
+    "dateExpiryYear": "29",
+    "type": "visa"
+  },
+  "cvc2ResultCode": "P",
+  "isSurcharge": false,
+  "amountTotal": "1.00",
+  "liabilityIndicator": "standard",
+  "links": [
+    {
+      "href": "https://uat.windcave.com/api/v1/transactions/00000004018b76c6",
+      "rel": "self",
+      "method": "GET"
+    },
+    {
+      "href": "https://uat.windcave.com/api/v1/transactions/00000004018b74de",
+      "rel": "parent",
+      "method": "GET"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/tests/Mock/RefundSuccess.txt b/tests/Mock/RefundSuccess.txt
new file mode 100644
index 0000000..04e043d
--- /dev/null
+++ b/tests/Mock/RefundSuccess.txt
@@ -0,0 +1,57 @@
+HTTP/1.1 200 OK
+Date: Thu, 01 May 2025 01:43:28 GMT
+Content-Type: application/json; charset=utf-8
+
+{
+  "id": "refundtransaction123",
+  "username": "merchant",
+  "authorised": true,
+  "allowRetry": false,
+  "retryIndicator": "",
+  "reCo": "00",
+  "responseText": "APPROVED",
+  "authCode": "001412",
+  "acquirer": {
+    "name": "Undefined",
+    "mid": "10000000",
+    "tid": "10001548",
+    "reCo": "00",
+    "responseText": "APPROVED"
+  },
+  "type": "refund",
+  "method": "card",
+  "localTimeZone": "UK_GMT",
+  "dateTimeUtc": "2025-08-19T01:34:55Z",
+  "dateTimeLocal": "2025-08-19T02:34:55+01:00",
+  "settlementDate": "2025-08-19",
+  "amount": "1.00",
+  "balanceAmount": "0.00",
+  "currency": "GBP",
+  "currencyNumeric": 826,
+  "clientType": "internet",
+  "merchantReference": "test1755567267ref",
+  "card": {
+    "cardNumber2": "9310200000000010",
+    "cardHolderName": "WHPP",
+    "cardNumber": "411111......1111",
+    "dateExpiryMonth": "02",
+    "dateExpiryYear": "29",
+    "type": "visa"
+  },
+  "cvc2ResultCode": "P",
+  "isSurcharge": false,
+  "amountTotal": "1.00",
+  "liabilityIndicator": "standard",
+  "links": [
+    {
+      "href": "https://uat.windcave.com/api/v1/transactions/00000004018b76c6",
+      "rel": "self",
+      "method": "GET"
+    },
+    {
+      "href": "https://uat.windcave.com/api/v1/transactions/00000004018b74de",
+      "rel": "parent",
+      "method": "GET"
+    }
+  ]
+}
\ No newline at end of file