t.Fatalf("unexpected err: %v", err)
	}
	proxy, err := http.ProxyFromEnvironment(req)
	if err != nil {
		t.Fatalf("unexpected err: %v", err)
	}
	if proxy == nil {
		t.Skip("test skipped as ProxyFromEnvironment already initialized in environment without defined HTTP proxy")
	}
	t.Log("http.ProxyFromEnvironment is usable, continue executing test")
}

func TestKubeletVersionCheck(t *testing.T) {

	}

	// For more details about various values used here refer
	// https://golang.org/pkg/net/http/#Transport documentation
	tr := &http.Transport{
		Proxy:                 http.ProxyFromEnvironment,
		DialContext:           dialContext,
		MaxIdleConnsPerHost:   maxIdleConnsPerHost,
		WriteBufferSize:       WriteBufferSize,
		ReadBufferSize:        ReadBufferSize,
		IdleConnTimeout:       15 * time.Second,

		}
		url.Scheme = "https"
		source = url.String()
	}

	client := &http.Client{
		Transport: &http.Transport{
			ResponseHeaderTimeout: timeout + 5*time.Second,
			Proxy:                 http.ProxyFromEnvironment,
			TLSClientConfig:       tlsConfig,
		},
	}
	resp, err := client.Get(source)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {

		}

		config := &tls.Config{
			ServerName: u.Hostname(),
			RootCAs:    caCertPool,
			MinVersion: tls.VersionTLS12,
		}

		httpClient.Transport = &http.Transport{
			Proxy:           http.ProxyFromEnvironment,
			TLSClientConfig: config,
			DialContext: (&net.Dialer{
				Timeout: time.Second * 10,
			}).DialContext,
			IdleConnTimeout:       90 * time.Second,
			TLSHandshakeTimeout:   10 * time.Second,

	return sha256Sum, releaseTime, releaseInfo, err
}

func getUpdateTransport(timeout time.Duration) http.RoundTripper {
	var updateTransport http.RoundTripper = &http.Transport{
		Proxy:                 http.ProxyFromEnvironment,
		DialContext:           xhttp.NewInternodeDialContext(timeout, globalTCPOptions),
		IdleConnTimeout:       timeout,
		TLSHandshakeTimeout:   timeout,
		ExpectContinueTimeout: timeout,

// as directed by the environment variables HTTP_PROXY, HTTPS_PROXY
// and NO_PROXY (or the lowercase versions thereof).
var DefaultTransport RoundTripper = &Transport{
	Proxy: ProxyFromEnvironment,
	DialContext: defaultTransportDialContext(&net.Dialer{
		Timeout:   30 * time.Second,
		KeepAlive: 30 * time.Second,
	}),
	ForceAttemptHTTP2:     true,
	MaxIdleConns:          100,

			os.Setenv("HTTP_PROXY", tt.env)
			os.Setenv("HTTPS_PROXY", tt.httpsenv)
			os.Setenv("NO_PROXY", tt.noenv)
			os.Setenv("REQUEST_METHOD", tt.reqmeth)
			ResetCachedEnvironment()
			return ProxyFromEnvironment(req)
		})
	}
}

func TestProxyFromEnvironmentLowerCase(t *testing.T) {
	ResetProxyEnv()
	defer ResetProxyEnv()
	for _, tt := range proxyFromEnvTests {