Add a unit test

Author: sjbronner

tests/Unit/CacheKeyTest.php

@@ -0,0 +1,23 @@
+<?php namespace GeneaLabs\LaravelModelCaching\Tests\Unit;
+
+use GeneaLabs\LaravelModelCaching\CachedBuilder;
+use GeneaLabs\LaravelModelCaching\Tests\Fixtures\Author;
+use GeneaLabs\LaravelModelCaching\Tests\UnitTestCase;
+use ReflectionMethod;
+
+class CacheKeyTest extends UnitTestCase
+{
+    public function testKeyIsSHA1()
+    {
+        $makeCacheKey = new ReflectionMethod(
+            CachedBuilder::class,
+            'makeCacheKey'
+        );
+        $makeCacheKey->setAccessible(true);
+
+        $builder = (new Author)->startsWithA();
+        $key = $makeCacheKey->invoke($builder);
+
+        $this->assertTrue(strlen($key) === 40 && ctype_xdigit($key));
+    }
+}