Add test for is_system_admin helper

tests/Unit/Helpers/IsSystemAdminHelperTest.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace Tests\Unit\Helpers;
+
+use App\User;
+use Tests\TestCase;
+
+class IsSystemAdminHelperTest extends TestCase
+{
+    /** @test */
+    public function user_is_an_admin()
+    {
+        $adminEmail1 = 'admin1@example.net';
+        $adminEmail2 = 'admin2@example.net';
+        putenv('SYSTEM_ADMIN_EMAILS='.$adminEmail1.';'.$adminEmail2);
+
+        $admin1 = factory(User::class)->make(['email' => $adminEmail1]);
+        $admin2 = factory(User::class)->make(['email' => $adminEmail2]);
+        $userWithEmail = factory(User::class)->make(['email' => 'user@example.net']);
+        $userWithNoEmail = factory(User::class)->make(['email' => null]);
+
+        $this->assertTrue(is_system_admin($admin1));
+        $this->assertTrue(is_system_admin($admin2));
+        $this->assertFalse(is_system_admin($userWithEmail));
+        $this->assertFalse(is_system_admin($userWithNoEmail));
+    }
+}