I have a simple GenServer making an HTTP request

defmodule GamePlay do
  use GenServer

  alias Wrapper

  def start_link(_args) do
    GenServer.start_link(__MODULE__, %{}, name: __MODULE__)
  end

  def init(state) do
    {:ok, state, {:continue, :put_mapping}}
  end

  def handle_continue(:put_mapping, state) do
    mapping = %{
      "index_patterns" => ["game_play-*"],
        }
      }
    }

    config = Application.get_env(:search_flask, :elasticsearch_seeds, [])

    if Keyword.get(config, :enabled?, true) do
      Wrapper.create_template_mappings("game_play", mapping)
    end

    {:noreply, state}
  end
end

and I am trying to put to test using Req, in Wrapper, I am sending an HTTP request using Req. but it only works once when I delete _build/test folder after that it stops working

defmodule GamePlayTest do
  use ExUnit.Case, async: true

  alias GamePlay
  alias Wrapper

  describe "GamePlay" do
    setup do
      on_exit(fn ->
        Req.Test.verify_on_exit!()
      end)

      :ok
    end

    test "sends the correct request to Elasticsearch" do
      Req.Test.stub(Wrapper, fn conn ->
        Req.Test.json(
          conn,
          %{"acknowledged" => true}
        )
      end)

      assert {:ok, pid} = GamePlay.start_link(%{})

      assert %Req.Response{body: %{"acknowledged" => true}, status: 200} =
               Req.get!(Application.get_env(:search_flask, :elasticsearch_req_options, []))
    end
  end
end

the test is simple as well but it only reaches to Wrapper.create_template_mappings only once after that it just keep failing. Any guidance will be appreciated, I think I need to flush or clean some process but I am not getting to that somehow, that where it should be done. Thank you