diff --git a/src/Controller/LoginController.php b/src/Controller/LoginController.php
index 82592c2..fb5573a 100644
--- a/src/Controller/LoginController.php
+++ b/src/Controller/LoginController.php
@@ -1,5 +1,6 @@
 <?php namespace MapGuesser\Controller;
 
+use MapGuesser\Http\Request;
 use MapGuesser\Interfaces\Request\IRequest;
 use MapGuesser\Interfaces\Response\IContent;
 use MapGuesser\Interfaces\Response\IRedirect;
@@ -49,7 +50,7 @@ class LoginController
 
         $this->request->session()->set('oauth_state', $state);
 
-        $oAuth = new GoogleOAuth();
+        $oAuth = new GoogleOAuth(new Request());
         $url = $oAuth->getDialogUrl($state, $this->request->getBase() . '/' . \Container::$routeCollection->getRoute('login-google-action')->generateLink());
 
         return new Redirect($url, IRedirect::TEMPORARY);
@@ -147,7 +148,7 @@ class LoginController
             return new HtmlContent('login/google_login', $data);
         }
 
-        $oAuth = new GoogleOAuth();
+        $oAuth = new GoogleOAuth(new Request());
         $tokenData = $oAuth->getToken($this->request->query('code'), $this->request->getBase() . '/' . \Container::$routeCollection->getRoute('login-google-action')->generateLink());
 
         if (!isset($tokenData['id_token'])) {
diff --git a/src/Http/Request.php b/src/Http/Request.php
index 2e5426a..9f1a05b 100644
--- a/src/Http/Request.php
+++ b/src/Http/Request.php
@@ -1,11 +1,10 @@
 <?php namespace MapGuesser\Http;
 
-class Request
+use MapGuesser\Interfaces\Http\IRequest;
+use MapGuesser\Interfaces\Http\IResponse;
+
+class Request implements IRequest
 {
-    const HTTP_GET = 0;
-
-    const HTTP_POST = 1;
-
     private string $url;
 
     private int $method;
@@ -14,12 +13,22 @@ class Request
 
     private array $headers = [];
 
-    public function __construct(string $url, int $method = self::HTTP_GET)
+    public function __construct(string $url = '', int $method = self::HTTP_GET)
     {
         $this->url = $url;
         $this->method = $method;
     }
 
+    public function setUrl(string $url): void
+    {
+        $this->url = $url;
+    }
+
+    public function setMethod(int $method): void
+    {
+        $this->method = $method;
+    }
+
     public function setQuery($query)
     {
         if (is_string($query)) {
@@ -34,7 +43,7 @@ class Request
         $this->headers = array_merge($this->headers, $headers);
     }
 
-    public function send(): Response
+    public function send(): IResponse
     {
         $ch = curl_init();
 
diff --git a/src/Http/Response.php b/src/Http/Response.php
index 9bee447..65958b0 100644
--- a/src/Http/Response.php
+++ b/src/Http/Response.php
@@ -1,6 +1,8 @@
 <?php namespace MapGuesser\Http;
 
-class Response
+use MapGuesser\Interfaces\Http\IResponse;
+
+class Response implements IResponse
 {
     private string $body;
 
diff --git a/src/Interfaces/Http/IRequest.php b/src/Interfaces/Http/IRequest.php
new file mode 100644
index 0000000..10436f7
--- /dev/null
+++ b/src/Interfaces/Http/IRequest.php
@@ -0,0 +1,18 @@
+<?php namespace MapGuesser\Interfaces\Http;
+
+interface IRequest
+{
+    const HTTP_GET = 0;
+
+    const HTTP_POST = 1;
+
+    public function setUrl(string $url): void;
+
+    public function setMethod(int $method): void;
+
+    public function setQuery($query);
+
+    public function setHeaders(array $headers);
+
+    public function send(): IResponse;
+}
diff --git a/src/Interfaces/Http/IResponse.php b/src/Interfaces/Http/IResponse.php
new file mode 100644
index 0000000..b840bac
--- /dev/null
+++ b/src/Interfaces/Http/IResponse.php
@@ -0,0 +1,8 @@
+<?php namespace MapGuesser\Interfaces\Http;
+
+interface IResponse
+{
+    public function getBody();
+
+    public function getHeaders();
+}
diff --git a/src/OAuth/GoogleOAuth.php b/src/OAuth/GoogleOAuth.php
index 07c2107..c339179 100644
--- a/src/OAuth/GoogleOAuth.php
+++ b/src/OAuth/GoogleOAuth.php
@@ -1,6 +1,6 @@
 <?php namespace MapGuesser\OAuth;
 
-use MapGuesser\Http\Request;
+use MapGuesser\Interfaces\Http\IRequest;
 
 class GoogleOAuth
 {
@@ -8,6 +8,13 @@ class GoogleOAuth
 
     private static $tokenUrlBase = 'https://oauth2.googleapis.com/token';
 
+    private IRequest $request;
+
+    public function __construct(IRequest $request)
+    {
+        $this->request = $request;
+    }
+
     public function getDialogUrl(string $state, string $redirectUrl): string
     {
         $oauthParams = [
@@ -32,9 +39,10 @@ class GoogleOAuth
             'grant_type' => 'authorization_code',
         ];
 
-        $request = new Request(self::$tokenUrlBase, Request::HTTP_POST);
-        $request->setQuery($tokenParams);
-        $response = $request->send();
+        $this->request->setUrl(self::$tokenUrlBase);
+        $this->request->setMethod(IRequest::HTTP_POST);
+        $this->request->setQuery($tokenParams);
+        $response = $this->request->send();
 
         return json_decode($response->getBody(), true);
     }
diff --git a/tests/OAuth/GoogleOAuthTest.php b/tests/OAuth/GoogleOAuthTest.php
new file mode 100644
index 0000000..a40fc66
--- /dev/null
+++ b/tests/OAuth/GoogleOAuthTest.php
@@ -0,0 +1,90 @@
+<?php
+
+namespace MapGuesser\Tests\OAuth;
+
+use MapGuesser\Interfaces\Http\IRequest;
+use MapGuesser\Interfaces\Http\IResponse;
+use MapGuesser\OAuth\GoogleOAuth;
+use PHPUnit\Framework\TestCase;
+
+final class GoogleOAuthTest extends TestCase
+{
+    public function testCanCreateDialogUrl(): void
+    {
+        $_ENV['GOOGLE_OAUTH_CLIENT_ID'] = 'xyz';
+        $state = 'random_state_string';
+        $redirectUrl = 'http://example.com/oauth';
+
+        $requestMock = $this->getMockBuilder(IRequest::class)
+            ->setMethods(['setUrl', 'setMethod', 'setQuery', 'setHeaders', 'send'])
+            ->getMock();
+        $googleOAuth = new GoogleOAuth($requestMock);
+
+        $dialogUrl = $googleOAuth->getDialogUrl($state, $redirectUrl);
+        $dialogUrlParsed = explode('?', $dialogUrl);
+
+        $this->assertEquals('https://accounts.google.com/o/oauth2/v2/auth', $dialogUrlParsed[0]);
+
+        parse_str($dialogUrlParsed[1], $dialogUrlQueryParams);
+
+        $expectedQueryParams = [
+            'response_type' => 'code',
+            'client_id' => $_ENV['GOOGLE_OAUTH_CLIENT_ID'],
+            'scope' => 'openid email',
+            'redirect_uri' => $redirectUrl,
+            'state' => $state,
+            'nonce' => hash('sha256', random_bytes(10) . microtime()),
+        ];
+
+        $this->assertEquals($expectedQueryParams['response_type'], $dialogUrlQueryParams['response_type']);
+        $this->assertEquals($expectedQueryParams['client_id'], $dialogUrlQueryParams['client_id']);
+        $this->assertEquals($expectedQueryParams['scope'], $dialogUrlQueryParams['scope']);
+        $this->assertEquals($expectedQueryParams['redirect_uri'], $dialogUrlQueryParams['redirect_uri']);
+        $this->assertEquals($expectedQueryParams['state'], $dialogUrlQueryParams['state']);
+        $this->assertMatchesRegularExpression('/^[a-f0-9]{64}$/', $dialogUrlQueryParams['nonce']);
+    }
+
+    public function testCanRequestToken(): void
+    {
+        $_ENV['GOOGLE_OAUTH_CLIENT_ID'] = 'abc';
+        $_ENV['GOOGLE_OAUTH_CLIENT_SECRET'] = 'xxx';
+        $code = 'code_from_google';
+        $redirectUrl = 'http://example.com/oauth';
+
+        $requestMock = $this->getMockBuilder(IRequest::class)
+            ->setMethods(['setUrl', 'setMethod', 'setQuery', 'setHeaders', 'send'])
+            ->getMock();
+        $responseMock = $this->getMockBuilder(IResponse::class)
+            ->setMethods(['getBody', 'getHeaders'])
+            ->getMock();
+        $googleOAuth = new GoogleOAuth($requestMock);
+
+        $expectedQueryParams = [
+            'code' => $code,
+            'client_id' => $_ENV['GOOGLE_OAUTH_CLIENT_ID'],
+            'client_secret' => $_ENV['GOOGLE_OAUTH_CLIENT_SECRET'],
+            'redirect_uri' => $redirectUrl,
+            'grant_type' => 'authorization_code',
+        ];
+
+        $requestMock->expects($this->once())
+            ->method('setUrl')
+            ->with($this->equalTo('https://oauth2.googleapis.com/token'));
+        $requestMock->expects($this->once())
+            ->method('setMethod')
+            ->with($this->equalTo(IRequest::HTTP_POST));
+        $requestMock->expects($this->once())
+            ->method('setQuery')
+            ->with($this->equalTo($expectedQueryParams));
+        $requestMock->expects($this->once())
+            ->method('send')
+            ->will($this->returnValue($responseMock));
+        $responseMock->expects($this->once())
+            ->method('getBody')
+            ->will($this->returnValue('{"test":"json"}'));
+
+        $token = $googleOAuth->getToken($code, $redirectUrl);
+
+        $this->assertEquals(['test' => 'json'], $token);
+    }
+}
diff --git a/tests/PersistentData/Model/ModelTest.php b/tests/PersistentData/Model/ModelTest.php
new file mode 100644
index 0000000..6e0b042
--- /dev/null
+++ b/tests/PersistentData/Model/ModelTest.php
@@ -0,0 +1,89 @@
+<?php namespace MapGuesser\Tests\Util;
+
+use MapGuesser\PersistentData\Model\Model;
+use PHPUnit\Framework\TestCase;
+
+class DummyModel extends Model
+{
+    protected static string $table = 'test_table';
+
+    protected static array $fields = ['name', 'valid'];
+
+    protected static array $relations = ['other_model' => OtherModel::class];
+
+    private string $name;
+
+    private bool $valid;
+
+    public function setName(string $name): void
+    {
+        $this->name = $name;
+    }
+
+    public function setValid(bool $valid): void
+    {
+        $this->valid = $valid;
+    }
+
+    public function getName(): string
+    {
+        return $this->name;
+    }
+
+    public function getValid(): bool
+    {
+        return $this->valid;
+    }
+}
+
+final class ModelTest extends TestCase
+{
+    public function testCanReturnTable(): void
+    {
+        $this->assertEquals('test_table', DummyModel::getTable());
+    }
+
+    public function testCanReturnFields(): void
+    {
+        $this->assertEquals(['id', 'name', 'valid'], DummyModel::getFields());
+    }
+
+    public function testCanReturnRelations(): void
+    {
+        $this->assertEquals(['other_model' => OtherModel::class], DummyModel::getRelations());
+    }
+
+    public function testCanBeConvertedToArray(): void
+    {
+        $model = new DummyModel();
+        $model->setId(123);
+        $model->setName('John');
+        $model->setValid(true);
+
+        $this->assertEquals([
+            'id' => 123,
+            'name' => 'John',
+            'valid' => true
+        ], $model->toArray());
+    }
+
+    public function testCanSaveAndResetSnapshot(): void
+    {
+        $model = new DummyModel();
+        $model->setId(123);
+        $model->setName('John');
+        $model->setValid(true);
+
+        $model->saveSnapshot();
+
+        $this->assertEquals([
+            'id' => 123,
+            'name' => 'John',
+            'valid' => true
+        ], $model->getSnapshot());
+
+        $model->resetSnapshot();
+
+        $this->assertEquals([], $model->getSnapshot());
+    }
+}
diff --git a/tests/Util/JwtParserTest.php b/tests/Util/JwtParserTest.php
new file mode 100644
index 0000000..468f93b
--- /dev/null
+++ b/tests/Util/JwtParserTest.php
@@ -0,0 +1,51 @@
+<?php namespace MapGuesser\Tests\Util;
+
+use MapGuesser\Util\JwtParser;
+use PHPUnit\Framework\TestCase;
+
+final class JwtParserTest extends TestCase
+{
+    private JwtParser $jwtParser;
+
+    protected function setUp(): void
+    {
+        $this->jwtParser = new JwtParser(
+            'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c'
+        );
+    }
+
+    public function testSettingTokenIsTheSameAsCreatingWithToken(): void
+    {
+        $jwtParser2 = new JwtParser();
+        $jwtParser2->setToken(
+            'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c'
+        );
+
+        $this->assertEquals($this->jwtParser, $jwtParser2);
+    }
+
+    public function testCanParseTokenHeader(): void
+    {
+        $this->assertEquals([
+            'alg' => 'HS256',
+            'typ' => 'JWT'
+        ], $this->jwtParser->getHeader());
+    }
+
+    public function testCanParseTokenPayload(): void
+    {
+        $this->assertEquals([
+            'sub' => '1234567890',
+            'name' => 'John Doe',
+            'iat' => 1516239022
+        ], $this->jwtParser->getPayload());
+    }
+
+    public function testCanParseTokenSignature(): void
+    {
+        $this->assertEquals(
+            '49f94ac7044948c78a285d904f87f0a4c7897f7e8f3a4eb2255fda750b2cc397',
+            bin2hex($this->jwtParser->getSignature())
+        );
+    }
+}