Prepare dateDifference helper test

tests/Unit/Helpers/DateDifferenceTest.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Tests\Unit\Helpers;
+
+use Tests\TestCase;
+
+/**
+ * Date Difference Helper Unit Test.
+ *
+ * @author Nafies Luthfi <nafiesL@gmail.com>
+ */
+class DateDifferenceTest extends TestCase
+{
+    /** @test */
+    public function date_difference_function_exists()
+    {
+        $this->assertTrue(function_exists('dateDifference'));
+    }
+}