response, err := s.client.Do(request)
	c.Assert(err, nil)
	c.Assert(response.StatusCode, http.StatusOK)

	// create HTTP request for listing buckets.
	request, err = newTestSignedRequest(http.MethodGet, getListBucketURL(s.endPoint),
		0, nil, s.accessKey, s.secretKey, s.signer)
	c.Assert(err, nil)

	// execute the HTTP request to list buckets.
	response, err = s.client.Do(request)
	c.Assert(err, nil)