diff --git a/tests/Unit/CostarTest.php b/tests/Unit/CostarTest.php
new file mode 100644
index 000000000..3e4961b43
--- /dev/null
+++ b/tests/Unit/CostarTest.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Tests\Unit;
+
+use App\Util\ActivityPub\Helpers;
+use Tests\TestCase;
+use Illuminate\Foundation\Testing\WithFaker;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+
+class CostarTest extends TestCase
+{
+    /** @test */
+    public function blockedDomain()
+    {
+    	$domains = config('costar.domain.block');
+        $this->assertTrue(in_array('example.net', $domains));
+
+        $blockedDomain = 'https://example.org/user/replyGuy';
+        $this->assertFalse(Helpers::validateUrl($blockedDomain));
+
+        $unblockedDomain = 'https://pixelfed.org/user/pixelfed';
+        $this->assertEquals(Helpers::validateUrl($unblockedDomain), $unblockedDomain);
+    }
+}