Testing Chunked responses from a phoenix endpoint using `Plug.Test` or `Phoenix.ConnTest`

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I am resurrecting this topic to share that you can test chunk responses if you follow the documentation for chunk. The test adapter collects chunks and updates the response body.

defp send_csv_response(%Plug.Conn{} = conn, _) do
  {:ok, %Plug.Conn{state: :chunked} = conn} =
    conn
    |> put_resp_content_type("text/csv")
    |> put_resp_header("content-disposition", ~s|attachment; filename="foo.csv"|)
    |> send_chunked(:ok)

  Enum.reduce_while(["a", "b", "c"], conn, fn data, conn ->
    case chunk(conn, data) do
      {:ok, conn} -> {:cont, conn}
      {:error, :closed} -> {:halt, conn}
    end
  end)
end

And in tests

test "chunked response", %{conn: conn} do
  %Plug.Conn{state: :chunked} = response = conn |> get(page_path(conn, :send_csv_response)
  content = response(response, 200)
  assert content == "abc"
end
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