horizonclient: Set default HTTP client (#1228)

* set default HTTP client

* changes from review

clients/horizonclient/client.go

@@ -53,7 +53,7 @@ func (c *Client) sendRequestURL(requestURL string, method string, a interface{})
 		return errors.Wrap(err, "error creating HTTP request")
 	}
 	c.setClientAppHeaders(req)
-
+	c.setDefaultClient()
 	if c.horizonTimeOut == 0 {
 		c.horizonTimeOut = HorizonTimeOut
 	}
@@ -93,6 +93,7 @@ func (c *Client) stream(
 			return errors.Wrap(err, "error creating HTTP request")
 		}
 		req.Header.Set("Accept", "text/event-stream")
+		c.setDefaultClient()
 		// to do: confirm name and version
 		c.setClientAppHeaders(req)
 
@@ -203,6 +204,13 @@ func (c *Client) setClientAppHeaders(req *http.Request) {
 	req.Header.Set("X-App-Version", c.AppVersion)
 }
 
+// setDefaultClient sets the default HTTP client when none is provided.
+func (c *Client) setDefaultClient() {
+	if c.HTTP == nil {
+		c.HTTP = http.DefaultClient
+	}
+}
+
 // fixHorizonURL strips all slashes(/) at the end of HorizonURL if any, then adds a single slash
 func (c *Client) fixHorizonURL() string {
 	return strings.TrimRight(c.HorizonURL, "/") + "/"

clients/horizonclient/main_test.go

@@ -2,6 +2,7 @@ package horizonclient
 
 import (
 	"fmt"
+	"net/http"
 	"testing"
 	"time"
 
@@ -293,6 +294,17 @@ func ExampleClient_Fund() {
 	fmt.Print(resp)
 }
 
+func TestFixHTTP(t *testing.T) {
+	client := &Client{
+		HorizonURL: "https://localhost/",
+	}
+	// No HTTP client is provided
+	assert.Nil(t, client.HTTP, "client HTTP is nil")
+	client.Root()
+	// When a request is made, default HTTP client is set
+	assert.IsType(t, client.HTTP, &http.Client{})
+}
+
 func TestClientFund(t *testing.T) {
 	hmock := httptest.NewClient()
 	client := &Client{