[Dembo] Add standard slack notification message

plugins/slack-notification-plugin/slack/message.go

@@ -1,5 +1,25 @@
 package slack
 
+import "encoding/json"
+
 type Message interface {
 	JSON() (string, error)
 }
+
+type standardMessage struct {
+	Text string `json:"text"`
+}
+
+func (message *standardMessage) JSON() (string, error) {
+	byteMessage, err := json.Marshal(message)
+	if err != nil {
+		return "", err
+	}
+	return string(byteMessage), nil
+}
+
+func NewStandardMessage(text string) Message {
+	return &standardMessage{
+		Text: text,
+	}
+}

plugins/slack-notification-plugin/slack/message_test.go

@@ -0,0 +1,13 @@
+package slack
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestStandardMessage_JSON(t *testing.T) {
+	message := NewStandardMessage("content")
+	result, err := message.JSON()
+	assert.NoError(t, err)
+	assert.Equal(t, "{\"text\":\"content\"}", result)
+}