add unit tests

tests/StorageAdapterFactoryTest.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace Tests;
+
+use Mockery;
+use PHPUnit\Framework\TestCase;
+use Prometheus\Storage\APC;
+use Prometheus\Storage\InMemory;
+use Prometheus\Storage\Redis;
+use Superbalist\LaravelPrometheusExporter\StorageAdapterFactory;
+
+class StorageAdapterFactoryTest extends TestCase
+{
+    public function testMakeMemoryAdapter()
+    {
+        $factory = new StorageAdapterFactory();
+        $adapter = $factory->make('memory');
+        $this->assertInstanceOf(InMemory::class, $adapter);
+    }
+
+    public function testMakeApcAdapter()
+    {
+        $factory = new StorageAdapterFactory();
+        $adapter = $factory->make('apc');
+        $this->assertInstanceOf(APC::class, $adapter);
+    }
+
+    public function testMakeRedisAdapter()
+    {
+        $factory = new StorageAdapterFactory();
+        $adapter = $factory->make('redis');
+        $this->assertInstanceOf(Redis::class, $adapter);
+    }
+
+    public function testMakeInvalidAdapter()
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('The driver [moo] is not supported.');
+
+        $factory = new StorageAdapterFactory();
+        $factory->make('moo');
+    }
+}