diff --git a/tests/ServerTest.php b/tests/ServerTest.php
index 3f823a17..2251258a 100644
--- a/tests/ServerTest.php
+++ b/tests/ServerTest.php
@@ -3,13 +3,21 @@
 namespace LeagueTests;
 
 use League\OAuth2\Server\Entities\ClientEntity;
+use League\OAuth2\Server\Exception\OAuthServerException;
+use League\OAuth2\Server\Grant\AuthCodeGrant;
 use League\OAuth2\Server\Grant\ClientCredentialsGrant;
 use League\OAuth2\Server\Repositories\AccessTokenRepositoryInterface;
+use League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface;
 use League\OAuth2\Server\Repositories\ClientRepositoryInterface;
+use League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface;
 use League\OAuth2\Server\Repositories\ScopeRepositoryInterface;
+use League\OAuth2\Server\Repositories\UserRepositoryInterface;
+use League\OAuth2\Server\ResponseTypes\BearerTokenResponse;
 use League\OAuth2\Server\Server;
 use LeagueTests\Stubs\StubResponseType;
+use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
+use Zend\Diactoros\ServerRequest;
 
 class ServerTest extends \PHPUnit_Framework_TestCase
 {
@@ -53,4 +61,80 @@ class ServerTest extends \PHPUnit_Framework_TestCase
         $response = $server->respondToRequest();
         $this->assertEquals(200, $response->getStatusCode());
     }
+
+    public function testRespondToRequestPsrResponse()
+    {
+        $client = new ClientEntity();
+        $client->setIdentifier('foo');
+        $client->setIdentifier('http://bar.com');
+
+        $clientRepository = $this->getMock(ClientRepositoryInterface::class);
+        $clientRepository->method('getClientEntity')->willReturn($client);
+
+        $server = new Server(
+            $clientRepository,
+            $this->getMock(AccessTokenRepositoryInterface::class),
+            $this->getMock(ScopeRepositoryInterface::class),
+            '',
+            '',
+            new StubResponseType()
+        );
+
+        $server->enableGrantType(
+            new AuthCodeGrant(
+                $this->getMock(AuthCodeRepositoryInterface::class),
+                $this->getMock(RefreshTokenRepositoryInterface::class),
+                $this->getMock(UserRepositoryInterface::class),
+                new \DateInterval('PT1H')
+            ),
+            new \DateInterval('PT1M')
+        );
+
+        $_SERVER['HTTP_HOST'] = 'http://auth.com';
+        $_SERVER['REQUEST_URI'] = '/auth';
+        $_GET['response_type'] = 'code';
+        $_GET['client_id'] = $client->getIdentifier();
+        $_GET['redirect_uri'] = $client->getRedirectUri();
+        $response = $server->respondToRequest();
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertTrue($response instanceof ResponseInterface);
+    }
+
+    public function testGetResponseType()
+    {
+        $clientRepository = $this->getMock(ClientRepositoryInterface::class);
+
+        $server = new Server(
+            $clientRepository,
+            $this->getMock(AccessTokenRepositoryInterface::class),
+            $this->getMock(ScopeRepositoryInterface::class),
+            '',
+            ''
+        );
+
+        $abstractGrantReflection = new \ReflectionClass($server);
+        $method = $abstractGrantReflection->getMethod('getResponseType');
+        $method->setAccessible(true);
+
+        $this->assertTrue($method->invoke($server) instanceof BearerTokenResponse);
+    }
+
+    public function testValidateRequest()
+    {
+        $clientRepository = $this->getMock(ClientRepositoryInterface::class);
+
+        $server = new Server(
+            $clientRepository,
+            $this->getMock(AccessTokenRepositoryInterface::class),
+            $this->getMock(ScopeRepositoryInterface::class),
+            '',
+            ''
+        );
+
+        try {
+            $server->validateRequest(new ServerRequest());
+        } catch (OAuthServerException $e) {
+            $this->assertEquals('Missing "Authorization" header', $e->getHint());
+        }
+    }
 }