Extract pure unit tests so that they can run fast

- Move to separate directory (base for a separate test suite)
- Inherit directly from PhpUnit
- Configure test suite with dedicated XML file

tests/unit/Api/ExceptionHandler/ModelNotFoundExceptionHandlerTest.php

@@ -0,0 +1,46 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Tests\unit\Api\ExceptionHandler;
+
+use Exception;
+use Flarum\Api\ExceptionHandler\ModelNotFoundExceptionHandler;
+use Illuminate\Database\Eloquent\ModelNotFoundException;
+use PHPUnit\Framework\TestCase;
+
+class ModelNotFoundExceptionHandlerTest extends TestCase
+{
+    private $handler;
+
+    public function setUp()
+    {
+        $this->handler = new ModelNotFoundExceptionHandler;
+    }
+
+    public function test_it_handles_recognisable_exceptions()
+    {
+        $this->assertFalse($this->handler->manages(new Exception));
+        $this->assertTrue($this->handler->manages(new ModelNotFoundException));
+    }
+
+    public function test_managing_exceptions()
+    {
+        $response = $this->handler->handle(new ModelNotFoundException);
+
+        $this->assertEquals(404, $response->getStatus());
+        $this->assertEquals([
+            [
+                'status' => '404',
+                'code' => 'resource_not_found'
+            ]
+        ], $response->getErrors());
+    }
+}