ConnCase: Make sure the host we use in tests is the actual Endpoint host

test/support/conn_case.ex

@@ -120,6 +120,10 @@ defp json_response_and_validate_schema(conn, _status) do
 
     Mox.verify_on_exit!()
 
-    {:ok, conn: Phoenix.ConnTest.build_conn()}
+    {:ok,
+     conn:
+       Phoenix.ConnTest.build_conn()
+       |> Map.put(:host, Pleroma.Web.Endpoint.host())
+       |> Plug.Test.init_test_session(%{})}
   end
 end