Allow http client to be configured per-request

environment.go

@@ -12,6 +12,7 @@ type Environment struct {
 	SiteName        string
 	ChargebeeDomain string
 	Protocol        string
+	HttpClient      *http.Client
 }
 
 var (
@@ -32,9 +33,14 @@ func Configure(key string, siteName string) {
 	}
 	DefaultEnv = Environment{Key: key, SiteName: siteName}
 }
+
 func WithHTTPClient(c *http.Client) {
-	httpClient = c
+	// I don't really like setting this on the default environment, but maintains
+	// backwards compatibility at least while having the ability for client to be
+	// configured differently.
+	DefaultEnv.HttpClient = c
 }
+
 func (env *Environment) apiBaseUrl() string {
 	if env.Protocol == "" {
 		env.Protocol = "https"

http_request.go

@@ -7,11 +7,32 @@ import (
 	"net/http"
 )
 
-var httpClient = &http.Client{Timeout: DefaultHTTPTimeout}
+// RequestOption allows you to pass along functions that customize a
+// RequestOptions struct.
+type RequestOption func(*RequestOptions)
+
+// HTTPOption contains a struct of various request options that could be
+//customized.
+type RequestOptions struct {
+	client *http.Client
+}
+
+// Client allows you to customize the http client on a per-request basis
+func SetClient(hc *http.Client) RequestOption {
+	return func(h *RequestOptions) {
+		h.client = hc
+	}
+}
 
 //Do is used to execute an API Request.
-func Do(req *http.Request) (string, error) {
-	response, err := httpClient.Do(req)
+func Do(req *http.Request, opts ...RequestOption) (string, error) {
+	reqOpts := RequestOptions{
+		client: &http.Client{},
+	}
+	for _, o := range opts {
+		o(&reqOpts)
+	}
+	response, err := reqOpts.client.Do(req)
 	if err != nil {
 		return "", err
 	}

list_request.go

@@ -10,7 +10,11 @@ func (request RequestObj) ListRequestWithEnv(env Environment) (*ResultList, erro
 	if err != nil {
 		panic(err)
 	}
-	res, err1 := Do(req)
+	opts := []RequestOption{}
+	if env.HttpClient != nil {
+		opts = append(opts, SetClient(env.HttpClient))
+	}
+	res, err1 := Do(req, opts...)
 	result := &ResultList{}
 	if err1 != nil {
 		return result, err1

request.go

@@ -17,7 +17,11 @@ func (request RequestObj) RequestWithEnv(env Environment) (*Result, error) {
 	if err != nil {
 		panic(err)
 	}
-	res, err1 := Do(req)
+	opts := []RequestOption{}
+	if env.HttpClient != nil {
+		opts = append(opts, SetClient(env.HttpClient))
+	}
+	res, err1 := Do(req, opts...)
 	result := &Result{}
 	if err1 != nil {
 		return result, err1