diff --git a/test/web/activity_pub/transmogrifier_test.exs b/test/web/activity_pub/transmogrifier_test.exs
index 6320b5b6e..b8adf3b8a 100644
--- a/test/web/activity_pub/transmogrifier_test.exs
+++ b/test/web/activity_pub/transmogrifier_test.exs
@@ -918,4 +918,42 @@ test "it rejects activities which reference objects that have an incorrect attri
       :error = Transmogrifier.handle_incoming(data)
     end
   end
+
+  describe "general origin containment" do
+    test "contain_origin_from_id() catches obvious spoofing attempts" do
+      data = %{
+        "id" => "http://example.com/~alyssa/activities/1234.json"
+      }
+
+      :error =
+        Transmogrifier.contain_origin_from_id(
+          "http://example.org/~alyssa/activities/1234.json",
+          data
+        )
+    end
+
+    test "contain_origin_from_id() allows alternate IDs within the same origin domain" do
+      data = %{
+        "id" => "http://example.com/~alyssa/activities/1234.json"
+      }
+
+      :ok =
+        Transmogrifier.contain_origin_from_id(
+          "http://example.com/~alyssa/activities/1234",
+          data
+        )
+    end
+
+    test "contain_origin_from_id() allows matching IDs" do
+      data = %{
+        "id" => "http://example.com/~alyssa/activities/1234.json"
+      }
+
+      :ok =
+        Transmogrifier.contain_origin_from_id(
+          "http://example.com/~alyssa/activities/1234.json",
+          data
+        )
+    end
+  end
 end