Allow for setting a custom HTTP client

rest.go

@@ -11,6 +11,7 @@ import (
 // Method contains the supported HTTP verbs.
 type Method string
 
+// Supported HTTP verbs.
 const (
 	Get    Method = "GET"
 	Post   Method = "POST"
@@ -28,6 +29,16 @@ type Request struct {
 	Body        []byte
 }
 
+// DefaultClient is used if no custom HTTP client is defined
+var DefaultClient = &Client{HTTPClient: http.DefaultClient}
+
+// Client allows modification of client headers, redirect policy
+// and other settings
+// See https://golang.org/pkg/net/http
+type Client struct {
+	HTTPClient *http.Client
+}
+
 // Response holds the response from an API call.
 type Response struct {
 	StatusCode int                 // e.g. 200
@@ -59,11 +70,7 @@ func BuildRequestObject(request Request) (*http.Request, error) {
 
 // MakeRequest makes the API call.
 func MakeRequest(req *http.Request) (*http.Response, error) {
-	var Client = &http.Client{
-		Transport: http.DefaultTransport,
-	}
-	res, err := Client.Do(req)
-	return res, err
+	return DefaultClient.HTTPClient.Do(req)
 }
 
 // BuildResponse builds the response struct.
@@ -83,6 +90,19 @@ func BuildResponse(res *http.Response) (*Response, error) {
 
 // API is the main interface to the API.
 func API(request Request) (*Response, error) {
+	return DefaultClient.API(request)
+}
+
+// The following functions enable the ability to define a
+// custom HTTP Client
+
+// MakeRequest makes the API call.
+func (c *Client) MakeRequest(req *http.Request) (*http.Response, error) {
+	return c.HTTPClient.Do(req)
+}
+
+// API is the main interface to the API.
+func (c *Client) API(request Request) (*Response, error) {
 	// Add any query parameters to the URL.
 	if len(request.QueryParams) != 0 {
 		request.BaseURL = AddQueryParameters(request.BaseURL, request.QueryParams)
@@ -95,7 +115,7 @@ func API(request Request) (*Response, error) {
 	}
 
 	// Build the HTTP client and make the request.
-	res, err := MakeRequest(req)
+	res, err := c.MakeRequest(req)
 	if err != nil {
 		return nil, err
 	}

rest_test.go

@@ -4,7 +4,9 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
+	"time"
 )
 
 func TestBuildURL(t *testing.T) {
@@ -47,6 +49,7 @@ func TestBuildResponse(t *testing.T) {
 	fakeServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		fmt.Fprintln(w, "{\"message\": \"success\"}")
 	}))
+	defer fakeServer.Close()
 	baseURL := fakeServer.URL
 	method := Get
 	request := Request{
@@ -74,6 +77,7 @@ func TestRest(t *testing.T) {
 	fakeServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		fmt.Fprintln(w, "{\"message\": \"success\"}")
 	}))
+	defer fakeServer.Close()
 	host := fakeServer.URL
 	endpoint := "/test_endpoint"
 	baseURL := host + endpoint
@@ -105,3 +109,27 @@ func TestRest(t *testing.T) {
 		t.Errorf("Rest failed to make a valid API request. Returned error: %v", e)
 	}
 }
+
+func TestCustomHTTPClient(t *testing.T) {
+	fakeServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		time.Sleep(time.Millisecond * 20)
+		fmt.Fprintln(w, "{\"message\": \"success\"}")
+	}))
+	defer fakeServer.Close()
+	host := fakeServer.URL
+	endpoint := "/test_endpoint"
+	baseURL := host + endpoint
+	method := Get
+	request := Request{
+		Method:  method,
+		BaseURL: baseURL,
+	}
+	customClient := &Client{&http.Client{Timeout: time.Millisecond * 10}}
+	_, err := customClient.API(request)
+	if err == nil {
+		t.Error("A timeout did not trigger as expected")
+	}
+	if strings.Contains(err.Error(), "Client.Timeout exceeded while awaiting headers") == false {
+		t.Error("We did not receive the Timeout error")
+	}
+}