Use NewRequestWithContext instead of nil checking (#200)

client.go

@@ -143,7 +143,7 @@ func (c *Client) Production() *Client {
 //
 // Use PushWithContext if you need better cancellation and timeout control.
 func (c *Client) Push(n *Notification) (*Response, error) {
-	return c.PushWithContext(nil, n)
+	return c.PushWithContext(context.Background(), n)
 }
 
 // PushWithContext sends a Notification to the APNs gateway. Context carries a
@@ -162,7 +162,7 @@ func (c *Client) PushWithContext(ctx Context, n *Notification) (*Response, error
 	}
 
 	url := fmt.Sprintf("%v/3/device/%v", c.Host, n.DeviceToken)
-	req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(payload))
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(payload))
 	if err != nil {
 		return nil, err
 	}
@@ -173,7 +173,7 @@ func (c *Client) PushWithContext(ctx Context, n *Notification) (*Response, error
 
 	setHeaders(req, n)
 
-	httpRes, err := c.requestWithContext(ctx, req)
+	httpRes, err := c.HTTPClient.Do(req)
 	if err != nil {
 		return nil, err
 	}
@@ -226,10 +226,3 @@ func setHeaders(r *http.Request, n *Notification) {
 	}
 
 }
-
-func (c *Client) requestWithContext(ctx Context, req *http.Request) (*http.Response, error) {
-	if ctx != nil {
-		req = req.WithContext(ctx)
-	}
-	return c.HTTPClient.Do(req)
-}

client_test.go

@@ -211,6 +211,21 @@ func TestClientPushWithContext(t *testing.T) {
 	assert.Equal(t, res.ApnsID, apnsID)
 }
 
+func TestClientPushWithNilContext(t *testing.T) {
+	n := mockNotification()
+	var apnsID = "02ABC856-EF8D-4E49-8F15-7B8A61D978D6"
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("apns-id", apnsID)
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	res, err := mockClient(server.URL).PushWithContext(nil, n)
+	assert.EqualError(t, err, "net/http: nil Context")
+	assert.Nil(t, res)
+}
+
 func TestHeaders(t *testing.T) {
 	n := mockNotification()
 	n.ApnsID = "84DB694F-464F-49BD-960A-D6DB028335C9"