Add ability to use custom HTTP client.

rest.go

@@ -19,6 +19,13 @@ const (
 	Delete Method = "DELETE"
 )
 
+var defaultClient = &Client{HTTPClient: http.DefaultClient}
+
+// Client performs API calls using its HTTP client.
+type Client struct {
+	HTTPClient *http.Client
+}
+
 // Request holds the request to an API Call.
 type Request struct {
 	Method      Method
@@ -59,11 +66,7 @@ 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 +86,11 @@ 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)
+}
+
+// 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 +103,7 @@ func API(request Request) (*Response, error) {
 	}
 
 	// Build the HTTP client and make the request.
-	res, err := MakeRequest(req)
+	res, err := c.HTTPClient.Do(req)
 	if err != nil {
 		return nil, err
 	}

rest_test.go

@@ -1,9 +1,11 @@
 package rest
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"testing"
 )
 
@@ -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 +109,29 @@ func TestRest(t *testing.T) {
 		t.Errorf("Rest failed to make a valid API request. Returned error: %v", e)
 	}
 }
+
+func TestCustomClient(t *testing.T) {
+	fakeServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, "{\"message\": \"success\"}")
+	}))
+	defer fakeServer.Close()
+	wantErr := errors.New("pass")
+	c := &Client{&http.Client{Transport: errorTransport{wantErr}}}
+	_, err := c.API(Request{BaseURL: fakeServer.URL})
+	if err == nil {
+		t.Error("got nil err, want %q", wantErr)
+	}
+	if urlError, ok := err.(*url.Error); ok {
+		if urlError.Err != wantErr {
+			t.Errorf("err: got %#v, want %q", err, wantErr)
+		}
+	}
+}
+
+type errorTransport struct {
+	err error
+}
+
+func (t errorTransport) RoundTrip(r *http.Request) (*http.Response, error) {
+	return nil, t.err
+}