Added some tests for the database setting repository

tests/Flarum/Core/Settings/DatabaseSettingsRepositoryTest.php

@@ -0,0 +1,33 @@
+<?php
+namespace tests\Flarum\Core\Settings;
+
+use Flarum\Core\Settings\DatabaseSettingsRepository;
+use Illuminate\Database\ConnectionInterface;
+use Mockery as m;
+use tests\Test\TestCase;
+
+class DatabaseSettingsRepositoryTest extends TestCase
+{
+    private $connection;
+    private $repository;
+
+    public function init()
+    {
+        $this->connection = m::mock(ConnectionInterface::class);
+        $this->repository = new DatabaseSettingsRepository($this->connection);
+    }
+    
+    public function test_requesting_an_existing_setting_should_return_its_value()
+    {
+        $this->connection->shouldReceive("table->where->pluck")->andReturn('value');
+
+        $this->assertEquals('value', $this->repository->get('key'));
+    }
+
+    public function test_non_existent_setting_values_should_return_null()
+    {
+        $this->connection->shouldReceive("table->where->pluck")->andReturn(null);
+
+        $this->assertEquals('default', $this->repository->get('key', 'default'));
+    }
+}