You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: roundtripper_test.go
    path of file: ./repos/gitlabhq/workhorse/internal/upstream/roundtripper
    
    the code of the file until where you have to start completion: package roundtripper

import (
	"crypto/tls"
	"crypto/x509"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strconv"
    
func testNewBackendRoundTripper(t *testing.T, ts *httptest.Server, tlsClientConfig *tls.Config, expectedResponseBody string) {
	t.Helper()

	backend, err := url.Parse(ts.URL)
	require.NoError(t, err, "parse url")

	rt := newBackendRoundTripper(backend, "", 0, true, tlsClientConfig)

	req, err := http.NewRequest("GET", ts.URL+"/", nil)
	require.NoError(t, err, "build request")

	response, err := rt.RoundTrip(req)
	require.NoError(t, err, "perform roundtrip")
	defer response.Body.Close()

	body, err := io.ReadAll(response.Body)
	require.NoError(t, err)

	require.Equal(t, expectedResponseBody, string(body))
}