res, err := s.client.Do(req)
	if err != nil {
		c.Fatal(err)
	}

	for k := range expectedMap {
		if v, ok := res.Header[k]; !ok {
			c.Errorf("Expected key %s missing from %v", k, res.Header)
		} else {
			expectedSet := set.CreateStringSet(expectedMap[k]...)
			gotSet := set.CreateStringSet(strings.Split(v[0], ", ")...)
			if !expectedSet.Equals(gotSet) {