refactor: Added msgerrors package and refactored code for safer error handling

msgerrors/msgerror.go

@@ -0,0 +1,46 @@
+package msgerrors
+
+import (
+	"errors"
+	"strings"
+)
+
+// MsgError wraps a slice of errors and provides convenient
+// syntax for processing individual errors without breaking
+// the service
+type MsgError struct {
+	err []string
+}
+
+// New instantiates a MsgError with a nil Err field
+func New() *MsgError {
+	return &MsgError{err: make([]string, 0, 0)}
+}
+
+// Append safely adds a new error to our list
+func (m *MsgError) Append(err error) {
+	if err != nil {
+		m.err = append(m.err, err.Error())
+	}
+}
+
+// Error provides the string output of our error
+// This allows MsgError to implement the core "error"
+// interface
+func (m *MsgError) Error() string {
+	if len(m.err) == 0 {
+		return ""
+	}
+	return strings.Join(m.err, "\n")
+}
+
+// Errors provides conventient syntax for returning
+// an error containing all information about the
+// accumulated errors in code. It will return
+// nil if no errors have been collated
+func (m *MsgError) Errors() error {
+	if len(m.err) == 0 {
+		return nil
+	}
+	return errors.New(m.Error())
+}

msgerrors/msgerror_test.go

@@ -0,0 +1,36 @@
+package msgerrors
+
+import (
+	"errors"
+	"strings"
+	"testing"
+)
+
+func TestMsgError(t *testing.T) {
+	msgErr := New()
+
+	if msgErr.Error() != "" {
+		t.Errorf("Expected empty string. Recieved %s", msgErr.Error())
+	}
+	if msgErr.Errors() != nil {
+		t.Errorf("Expected nil. Recieved %s", msgErr.Errors())
+	}
+
+	err1 := errors.New("Error 1")
+	err2 := errors.New("Error 2")
+	msgErr.Append(err1)
+	msgErr.Append(err2)
+
+	if len(msgErr.err) != 2 {
+		t.Errorf("Expected length 2. Recieved %d", len(msgErr.err))
+	}
+
+	concatenatedErr := strings.Join([]string{"Error 1", "Error 2"}, "\n")
+	if msgErr.Error() != concatenatedErr {
+		t.Errorf("Expected %s. \n Recieved %s", concatenatedErr, msgErr.Error())
+	}
+
+	if msgErr.Errors() == nil {
+		t.Errorf("Expected %s. \n Recieved %s", errors.New(concatenatedErr), msgErr.Errors())
+	}
+}

service/discord/discord.go

@@ -2,6 +2,7 @@ package discord
 
 import (
 	"github.com/bwmarrin/discordgo"
+	"github.com/nikoksr/notify/msgerrors"
 	"github.com/pkg/errors"
 )
 
@@ -90,13 +91,14 @@ func (d *Discord) AddReceivers(channelIDs ...string) {
 // Send takes a message subject and a message body and sends them to all previously set chats.
 func (d Discord) Send(subject, message string) error {
 	fullMessage := subject + "\n" + message // Treating subject as message title
-
+	msgErr := msgerrors.New()
 	for _, channelID := range d.channelIDs {
 		_, err := d.client.ChannelMessageSend(channelID, fullMessage)
 		if err != nil {
-			return errors.Wrapf(err, "failed to send message to Discord channel '%s'", channelID)
+			err = errors.Wrapf(err, "failed to send message to Discord channel '%s'", channelID)
+			msgErr.Append(err)
 		}
 	}
 
-	return nil
+	return msgErr.Errors()
 }

service/mail/mail.go

@@ -53,8 +53,8 @@ func (m Mail) Send(subject, message string) error {
 
 	err := msg.Send(m.smtpHostAddr, m.smtpAuth)
 	if err != nil {
-		err = errors.Wrap(err, "failed to send mail")
+		return errors.Wrap(err, "failed to send mail")
 	}
 
-	return err
+	return nil
 }

service/msteams/ms_teams.go

@@ -2,6 +2,7 @@ package msteams
 
 import (
 	goteamsnotify "github.com/atc0005/go-teams-notify/v2"
+	"github.com/nikoksr/notify/msgerrors"
 	"github.com/pkg/errors"
 )
 
@@ -47,13 +48,13 @@ func (m MSTeams) Send(subject, message string) error {
 	msgCard := goteamsnotify.NewMessageCard()
 	msgCard.Title = subject
 	msgCard.Text = message
-
+	msgErr := msgerrors.New()
 	for _, webHook := range m.webHooks {
 		err := m.client.Send(webHook, msgCard)
 		if err != nil {
-			return errors.Wrapf(err, "failed to send message to Microsoft Teams via webhook '%s'", webHook)
+			err := errors.Wrapf(err, "failed to send message to Microsoft Teams via webhook '%s'", webHook)
+			msgErr.Append(err)
 		}
 	}
-
-	return nil
+	return msgErr.Errors()
 }

service/pushbullet/pushbullet.go

@@ -2,6 +2,7 @@ package pushbullet
 
 import (
 	"github.com/cschomburg/go-pushbullet"
+	"github.com/nikoksr/notify/msgerrors"
 	"github.com/pkg/errors"
 )
 
@@ -36,17 +37,20 @@ func (pb *Pushbullet) AddReceivers(deviceNicknames ...string) {
 // (android, chrome, firefox, windows)
 // see https://www.pushbullet.com/apps
 func (pb Pushbullet) Send(subject, message string) error {
+	msgErr := msgerrors.New()
 	for _, deviceNickname := range pb.deviceNicknames {
 		dev, err := pb.client.Device(deviceNickname)
 		if err != nil {
-			return errors.Wrapf(err, "failed to find Pushbullet device with nickname '%s'", deviceNickname)
+			err = errors.Wrapf(err, "failed to find Pushbullet device with nickname '%s'", deviceNickname)
+			msgErr.Append(err)
+			continue
 		}
 
 		err = dev.PushNote(subject, message)
 		if err != nil {
-			return errors.Wrapf(err, "failed to send message to Pushbullet device with nickname '%s'", deviceNickname)
+			err = errors.Wrapf(err, "failed to send message to Pushbullet device with nickname '%s'", deviceNickname)
+			msgErr.Append(err)
 		}
 	}
-
-	return nil
+	return msgErr.Errors()
 }

service/pushbullet/sms.go

@@ -2,6 +2,7 @@ package pushbullet
 
 import (
 	"github.com/cschomburg/go-pushbullet"
+	"github.com/nikoksr/notify/msgerrors"
 	"github.com/pkg/errors"
 )
 
@@ -49,13 +50,13 @@ func (sms SMS) Send(subject, message string) error {
 	if err != nil {
 		return errors.Wrapf(err, "failed to find valid pushbullet user")
 	}
-
+	msgErr := msgerrors.New()
 	for _, phoneNumber := range sms.phoneNumbers {
 		err = sms.client.PushSMS(user.Iden, sms.deviceIdentifier, phoneNumber, fullMessage)
 		if err != nil {
-			return errors.Wrapf(err, "failed to send SMS message to %s via Pushbullet", phoneNumber)
+			err = errors.Wrapf(err, "failed to send SMS message to %s via Pushbullet", phoneNumber)
+			msgErr.Append(err)
 		}
 	}
-
-	return nil
+	return msgErr.Errors()
 }

service/slack/slack.go

@@ -1,6 +1,7 @@
 package slack
 
 import (
+	"github.com/nikoksr/notify/msgerrors"
 	"github.com/pkg/errors"
 	"github.com/slack-go/slack"
 )
@@ -36,16 +37,16 @@ func (s *Slack) AddReceivers(channelIDs ...string) {
 // see https://api.slack.com/
 func (s Slack) Send(subject, message string) error {
 	fullMessage := subject + "\n" + message // Treating subject as message title
-
+	msgErr := msgerrors.New()
 	for _, channelID := range s.channelIDs {
 		id, timestamp, err := s.client.PostMessage(
 			channelID,
 			slack.MsgOptionText(fullMessage, false),
 		)
 		if err != nil {
-			return errors.Wrapf(err, "failed to send message to Slack channel '%s' at time '%s'", id, timestamp)
+			err = errors.Wrapf(err, "failed to send message to Slack channel '%s' at time '%s'", id, timestamp)
+			msgErr.Append(err)
 		}
 	}
-
-	return nil
+	return msgErr.Errors()
 }

service/telegram/telegram.go

@@ -4,6 +4,7 @@ import (
 	"strconv"
 
 	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api"
+	"github.com/nikoksr/notify/msgerrors"
 	"github.com/pkg/errors"
 )
 
@@ -50,14 +51,14 @@ func (t Telegram) Send(subject, message string) error {
 
 	msg := tgbotapi.NewMessage(0, fullMessage)
 	msg.ParseMode = defaultParseMode
-
+	msgErr := msgerrors.New()
 	for _, chatID := range t.chatIDs {
 		msg.ChatID = chatID
 		_, err := t.client.Send(msg)
 		if err != nil {
-			return errors.Wrapf(err, "failed to send message to Telegram chat '%d'", chatID)
+			err = errors.Wrapf(err, "failed to send message to Telegram chat '%d'", chatID)
+			msgErr.Append(err)
 		}
 	}
-
-	return nil
+	return msgErr.Errors()
 }