diff --git a/app/Exceptions/DisplayException.php b/app/Exceptions/DisplayException.php
index 80c5771a5..aa18a1c1b 100644
--- a/app/Exceptions/DisplayException.php
+++ b/app/Exceptions/DisplayException.php
@@ -28,9 +28,9 @@ class DisplayException extends PterodactylException
      * @param string         $message
      * @param Throwable|null $previous
      * @param string         $level
-     * @internal param mixed $log
+     * @param int            $code
      */
-    public function __construct($message, Throwable $previous = null, $level = self::LEVEL_ERROR)
+    public function __construct($message, Throwable $previous = null, $level = self::LEVEL_ERROR, $code = 0)
     {
         $this->level = $level;
 
@@ -38,7 +38,7 @@ class DisplayException extends PterodactylException
             Log::{$level}($previous);
         }
 
-        parent::__construct($message);
+        parent::__construct($message, $code, $previous);
     }
 
     /**
diff --git a/tests/Traits/MocksRequestException.php b/tests/Traits/MocksRequestException.php
new file mode 100644
index 000000000..81e0e5414
--- /dev/null
+++ b/tests/Traits/MocksRequestException.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Tests\Traits;
+
+use Mockery;
+use Mockery\MockInterface;
+use GuzzleHttp\Exception\RequestException;
+
+trait MocksRequestException
+{
+    /**
+     * @var \GuzzleHttp\Exception\RequestException|\Mockery\Mock
+     */
+    private $exception;
+
+    /**
+     * @var mixed
+     */
+    private $exceptionResponse;
+
+    /**
+     * Configure the exception mock to work with the Panel's default exception
+     * handler actions.
+     */
+    public function configureExceptionMock()
+    {
+        $this->getExceptionMock()->shouldReceive('getResponse')->andReturn($this->exceptionResponse);
+    }
+
+    /**
+     * Return a mocked instance of the request exception.
+     *
+     * @return \Mockery\MockInterface
+     */
+    private function getExceptionMock(): MockInterface
+    {
+        return $this->exception ?? $this->exception = Mockery::mock(RequestException::class);
+    }
+
+    /**
+     * Set the exception response.
+     *
+     * @param mixed $response
+     */
+    protected function setExceptionResponse($response)
+    {
+        $this->exceptionResponse = $response;
+    }
+}
diff --git a/tests/Unit/Services/Allocations/SetDefaultAllocationServiceTest.php b/tests/Unit/Services/Allocations/SetDefaultAllocationServiceTest.php
new file mode 100644
index 000000000..72a837e78
--- /dev/null
+++ b/tests/Unit/Services/Allocations/SetDefaultAllocationServiceTest.php
@@ -0,0 +1,156 @@
+<?php
+
+namespace Tests\Unit\Services\Allocations;
+
+use Mockery as m;
+use Tests\TestCase;
+use Pterodactyl\Models\Server;
+use Pterodactyl\Models\Allocation;
+use Tests\Traits\MocksRequestException;
+use GuzzleHttp\Exception\RequestException;
+use Illuminate\Database\ConnectionInterface;
+use Pterodactyl\Exceptions\PterodactylException;
+use Pterodactyl\Contracts\Repository\ServerRepositoryInterface;
+use Pterodactyl\Services\Allocations\SetDefaultAllocationService;
+use Pterodactyl\Contracts\Repository\AllocationRepositoryInterface;
+use Pterodactyl\Exceptions\Http\Connection\DaemonConnectionException;
+use Pterodactyl\Contracts\Repository\Daemon\ServerRepositoryInterface as DaemonRepositoryInterface;
+
+class SetDefaultAllocationServiceTest extends TestCase
+{
+    use MocksRequestException;
+
+    /**
+     * @var \Illuminate\Database\ConnectionInterface|\Mockery\Mock
+     */
+    private $connection;
+
+    /**
+     * @var \Pterodactyl\Contracts\Repository\Daemon\ServerRepositoryInterface|\Mockery\Mock
+     */
+    private $daemonRepository;
+
+    /**
+     * @var \Pterodactyl\Contracts\Repository\AllocationRepositoryInterface|\Mockery\Mock
+     */
+    private $repository;
+
+    /**
+     * @var \Pterodactyl\Contracts\Repository\ServerRepositoryInterface|\Mockery\Mock
+     */
+    private $serverRepository;
+
+    /**
+     * Setup tests.
+     */
+    public function setUp()
+    {
+        parent::setUp();
+
+        $this->connection = m::mock(ConnectionInterface::class);
+        $this->daemonRepository = m::mock(DaemonRepositoryInterface::class);
+        $this->repository = m::mock(AllocationRepositoryInterface::class);
+        $this->serverRepository = m::mock(ServerRepositoryInterface::class);
+    }
+
+    /**
+     * Test that an allocation can be updated.
+     *
+     * @dataProvider useModelDataProvider
+     */
+    public function testAllocationIsUpdated(bool $useModel)
+    {
+        $allocations = factory(Allocation::class)->times(2)->make();
+        $model = factory(Server::class)->make();
+        if (! $useModel) {
+            $this->serverRepository->shouldReceive('find')->with(1234)->once()->andReturn($model);
+        }
+
+        $this->repository->shouldReceive('findWhere')->with([['server_id', '=', $model->id]])->once()->andReturn($allocations);
+        $this->connection->shouldReceive('beginTransaction')->withNoArgs()->once()->andReturnNull();
+        $this->serverRepository->shouldReceive('withoutFresh')->withNoArgs()->once()->andReturnSelf();
+        $this->serverRepository->shouldReceive('update')->with($model->id, [
+            'allocation_id' => $allocations->first()->id,
+        ])->once()->andReturnNull();
+
+        $this->daemonRepository->shouldReceive('setAccessServer')->with($model->uuid)->once()->andReturnSelf();
+        $this->daemonRepository->shouldReceive('setNode')->with($model->node_id)->once()->andReturnSelf();
+        $this->daemonRepository->shouldReceive('update')->with([
+            'build' => [
+                'default' => [
+                    'ip' => $allocations->first()->ip,
+                    'port' => $allocations->first()->port,
+                ],
+                'ports|overwrite' => $allocations->groupBy('ip')->map(function ($item) {
+                    return $item->pluck('port');
+                })->toArray(),
+            ],
+        ])->once()->andReturnNull();
+        $this->connection->shouldReceive('commit')->withNoArgs()->once()->andReturnNull();
+
+        $response = $this->getService()->handle($useModel ? $model : 1234, $allocations->first()->id);
+        $this->assertNotEmpty($response);
+        $this->assertSame($allocations->first(), $response);
+    }
+
+    /**
+     * Test that an allocation that doesn't belong to a server throws an exception.
+     *
+     * @expectedException \Pterodactyl\Exceptions\Service\Allocation\AllocationDoesNotBelongToServerException
+     */
+    public function testAllocationNotBelongingToServerThrowsException()
+    {
+        $model = factory(Server::class)->make();
+        $this->repository->shouldReceive('findWhere')->with([['server_id', '=', $model->id]])->once()->andReturn(collect());
+
+        $this->getService()->handle($model, 1234);
+    }
+
+    /**
+     * Test that an exception thrown by guzzle is handled properly.
+     */
+    public function testExceptionThrownByGuzzleIsHandled()
+    {
+        $this->configureExceptionMock();
+
+        $allocation = factory(Allocation::class)->make();
+        $model = factory(Server::class)->make();
+
+        $this->repository->shouldReceive('findWhere')->with([['server_id', '=', $model->id]])->once()->andReturn(collect([$allocation]));
+        $this->connection->shouldReceive('beginTransaction')->withNoArgs()->once()->andReturnNull();
+        $this->serverRepository->shouldReceive('withoutFresh')->withNoArgs()->once()->andReturnSelf();
+        $this->serverRepository->shouldReceive('update')->with($model->id, [
+            'allocation_id' => $allocation->id,
+        ])->once()->andReturnNull();
+
+        $this->daemonRepository->shouldReceive('setAccessServer->setNode->update')->once()->andThrow($this->getExceptionMock());
+        $this->connection->shouldReceive('rollBack')->withNoArgs()->once()->andReturnNull();
+
+        try {
+            $this->getService()->handle($model, $allocation->id);
+        } catch (PterodactylException $exception) {
+            $this->assertInstanceOf(DaemonConnectionException::class, $exception);
+            $this->assertInstanceOf(RequestException::class, $exception->getPrevious());
+        }
+    }
+
+    /**
+     * Data provider to determine if a model should be passed or an int.
+     *
+     * @return array
+     */
+    public function useModelDataProvider(): array
+    {
+        return [[false], [true]];
+    }
+
+    /**
+     * Return an instance of the service with mocked dependencies.
+     *
+     * @return \Pterodactyl\Services\Allocations\SetDefaultAllocationService
+     */
+    private function getService(): SetDefaultAllocationService
+    {
+        return new SetDefaultAllocationService($this->repository, $this->connection, $this->daemonRepository, $this->serverRepository);
+    }
+}
diff --git a/tests/Unit/Services/Databases/DatabasePasswordServiceTest.php b/tests/Unit/Services/Databases/DatabasePasswordServiceTest.php
index 099d44616..54d46b950 100644
--- a/tests/Unit/Services/Databases/DatabasePasswordServiceTest.php
+++ b/tests/Unit/Services/Databases/DatabasePasswordServiceTest.php
@@ -51,7 +51,7 @@ class DatabasePasswordServiceTest extends TestCase
      *
      * @dataProvider useModelDataProvider
      */
-    public function testPasswordIsChanged($useModel)
+    public function testPasswordIsChanged(bool $useModel)
     {
         $model = factory(Database::class)->make();
 
diff --git a/tests/Unit/Services/Databases/Hosts/HostDeletionServiceTest.php b/tests/Unit/Services/Databases/Hosts/HostDeletionServiceTest.php
index 402bf507c..bd927b8e8 100644
--- a/tests/Unit/Services/Databases/Hosts/HostDeletionServiceTest.php
+++ b/tests/Unit/Services/Databases/Hosts/HostDeletionServiceTest.php
@@ -51,7 +51,7 @@ class HostDeletionServiceTest extends TestCase
      *
      * @dataProvider databaseCountDataProvider
      */
-    public function testExceptionIsThrownIfDeletingHostWithDatabases($count)
+    public function testExceptionIsThrownIfDeletingHostWithDatabases(int $count)
     {
         $this->databaseRepository->shouldReceive('findCountWhere')->with([['database_host_id', '=', 1234]])->once()->andReturn($count);