Changes based on review comments:

1) Upgrade of sensu-plugins-go-library to version 0.2.0
2) Use of "github.com/sensu/sensu-go/api/core/v2" library instead of "github.com/sensu/sensu-go/types" to maintain consistency with sensu-go code

Gopkg.toml

@@ -31,7 +31,7 @@
 
 [[constraint]]
   name = "github.com/sensu/sensu-plugins-go-library"
-  version = "0.2.0-alpha4"
+  version = "0.2.0"
 
 [[constraint]]
   name = "github.com/stretchr/testify"

main.go

@@ -1,9 +1,8 @@
 package main
 
 import (
-	"errors"
 	"fmt"
-	"github.com/sensu/sensu-go/types"
+	corev2 "github.com/sensu/sensu-go/api/core/v2"
 	"github.com/sensu/sensu-plugins-go-library/sensu"
 	"strings"
 
@@ -18,6 +17,13 @@ type HandlerConfig struct {
 	SlackIconUrl    string
 }
 
+const (
+	webHookUrl = "webhook-url"
+	channel    = "channel"
+	userName   = "username"
+	iconUrl    = "icon-url"
+)
+
 var (
 	config = HandlerConfig{
 		PluginConfig: sensu.PluginConfig{
@@ -30,36 +36,36 @@ var (
 
 	slackConfigOptions = []*sensu.PluginConfigOption{
 		{
-			Path:      "webhook-url",
+			Path:      webHookUrl,
 			Env:       "SENSU_SLACK_WEHBOOK_URL",
-			Argument:  "webhook-url",
+			Argument:  webHookUrl,
 			Shorthand: "w",
 			Default:   "",
 			Usage:     "The webhook url to send messages to, defaults to value of SLACK_WEBHOOK_URL env variable",
 			Value:     &config.SlackWebhookUrl,
 		},
 		{
-			Path:      "channel",
+			Path:      channel,
 			Env:       "SENSU_SLACK_CHANNEL",
-			Argument:  "channel",
+			Argument:  channel,
 			Shorthand: "c",
 			Default:   "#general",
 			Usage:     "The channel to post messages to",
 			Value:     &config.SlackChannel,
 		},
 		{
-			Path:      "username",
+			Path:      userName,
 			Env:       "SENSU_SLACK_USERNAME",
-			Argument:  "username",
+			Argument:  userName,
 			Shorthand: "u",
 			Default:   "sensu",
 			Usage:     "The username that messages will be sent as",
 			Value:     &config.SlackUsername,
 		},
 		{
-			Path:      "icon-url",
+			Path:      iconUrl,
 			Env:       "SENSU_SLACK_ICON_URL",
-			Argument:  "icon-url",
+			Argument:  iconUrl,
 			Shorthand: "i",
 			Default:   "http://s3-us-west-2.amazonaws.com/sensuapp.org/sensu.png",
 			Usage:     "A URL to an image to use as the user avatar",
@@ -69,30 +75,19 @@ var (
 )
 
 func main() {
-	goHandler, _ := sensu.NewGoHandler(&config.PluginConfig, slackConfigOptions, checkArgs, executeHandler)
-	err := goHandler.Execute()
-	if err != nil {
-		fmt.Printf("Error executing plugin: %s", err)
-	}
+	goHandler := sensu.NewGoHandler(&config.PluginConfig, slackConfigOptions, checkArgs, sendMessage)
+	goHandler.Execute()
 }
 
-func checkArgs(_ *types.Event) error {
+func checkArgs(_ *corev2.Event) error {
 	if len(config.SlackWebhookUrl) == 0 {
-		return fmt.Errorf("--webhook-url or SENSU_SLACK_WEHBOOK_URL environment variable is required")
-	}
-
-	return nil
-}
-
-func executeHandler(event *types.Event) error {
-	if err := sendMessage(event); err != nil {
-		return errors.New(err.Error())
+		return fmt.Errorf("--webhook-url or SENSU_SLACK_WEBHOOK_URL environment variable is required")
 	}
 
 	return nil
 }
 
-func formattedEventAction(event *types.Event) string {
+func formattedEventAction(event *corev2.Event) string {
 	switch event.Check.Status {
 	case 0:
 		return "RESOLVED"
@@ -105,23 +100,23 @@ func chomp(s string) string {
 	return strings.Trim(strings.Trim(strings.Trim(s, "\n"), "\r"), "\r\n")
 }
 
-func eventKey(event *types.Event) string {
+func eventKey(event *corev2.Event) string {
 	return fmt.Sprintf("%s/%s", event.Entity.Name, event.Check.Name)
 }
 
-func eventSummary(event *types.Event, maxLength int) string {
+func eventSummary(event *corev2.Event, maxLength int) string {
 	output := chomp(event.Check.Output)
 	if len(event.Check.Output) > maxLength {
 		output = output[0:maxLength] + "..."
 	}
 	return fmt.Sprintf("%s:%s", eventKey(event), output)
 }
 
-func formattedMessage(event *types.Event) string {
+func formattedMessage(event *corev2.Event) string {
 	return fmt.Sprintf("%s - %s", formattedEventAction(event), eventSummary(event, 100))
 }
 
-func messageColor(event *types.Event) string {
+func messageColor(event *corev2.Event) string {
 	switch event.Check.Status {
 	case 0:
 		return "good"
@@ -132,7 +127,7 @@ func messageColor(event *types.Event) string {
 	}
 }
 
-func messageStatus(event *types.Event) string {
+func messageStatus(event *corev2.Event) string {
 	switch event.Check.Status {
 	case 0:
 		return "Resolved"
@@ -143,24 +138,24 @@ func messageStatus(event *types.Event) string {
 	}
 }
 
-func messageAttachment(event *types.Event) *slack.Attachment {
+func messageAttachment(event *corev2.Event) *slack.Attachment {
 	attachment := &slack.Attachment{
 		Title:    "Description",
 		Text:     event.Check.Output,
 		Fallback: formattedMessage(event),
 		Color:    messageColor(event),
 		Fields: []*slack.AttachmentField{
-			&slack.AttachmentField{
+			{
 				Title: "Status",
 				Value: messageStatus(event),
 				Short: false,
 			},
-			&slack.AttachmentField{
+			{
 				Title: "Entity",
 				Value: event.Entity.Name,
 				Short: true,
 			},
-			&slack.AttachmentField{
+			{
 				Title: "Check",
 				Value: event.Check.Name,
 				Short: true,
@@ -170,7 +165,7 @@ func messageAttachment(event *types.Event) *slack.Attachment {
 	return attachment
 }
 
-func sendMessage(event *types.Event) error {
+func sendMessage(event *corev2.Event) error {
 	hook := slack.NewWebHook(config.SlackWebhookUrl)
 	return hook.PostMessage(&slack.WebHookPostPayload{
 		Attachments: []*slack.Attachment{messageAttachment(event)},

main_test.go

@@ -8,14 +8,14 @@ import (
 	"os"
 	"testing"
 
-	"github.com/sensu/sensu-go/types"
+	corev2 "github.com/sensu/sensu-go/api/core/v2"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestFormattedEventAction(t *testing.T) {
 	assert := assert.New(t)
-	event := types.FixtureEvent("entity1", "check1")
+	event := corev2.FixtureEvent("entity1", "check1")
 
 	action := formattedEventAction(event)
 	assert.Equal("RESOLVED", action)
@@ -43,14 +43,14 @@ func TestChomp(t *testing.T) {
 
 func TestEventKey(t *testing.T) {
 	assert := assert.New(t)
-	event := types.FixtureEvent("entity1", "check1")
+	event := corev2.FixtureEvent("entity1", "check1")
 	eventKey := eventKey(event)
 	assert.Equal("entity1/check1", eventKey)
 }
 
 func TestEventSummary(t *testing.T) {
 	assert := assert.New(t)
-	event := types.FixtureEvent("entity1", "check1")
+	event := corev2.FixtureEvent("entity1", "check1")
 	event.Check.Output = "disk is full"
 
 	eventKey := eventSummary(event, 100)
@@ -62,7 +62,7 @@ func TestEventSummary(t *testing.T) {
 
 func TestFormattedMessage(t *testing.T) {
 	assert := assert.New(t)
-	event := types.FixtureEvent("entity1", "check1")
+	event := corev2.FixtureEvent("entity1", "check1")
 	event.Check.Output = "disk is full"
 	event.Check.Status = 1
 	formattedMsg := formattedMessage(event)
@@ -71,7 +71,7 @@ func TestFormattedMessage(t *testing.T) {
 
 func TestMessageColor(t *testing.T) {
 	assert := assert.New(t)
-	event := types.FixtureEvent("entity1", "check1")
+	event := corev2.FixtureEvent("entity1", "check1")
 
 	event.Check.Status = 0
 	color := messageColor(event)
@@ -88,7 +88,7 @@ func TestMessageColor(t *testing.T) {
 
 func TestMessageStatus(t *testing.T) {
 	assert := assert.New(t)
-	event := types.FixtureEvent("entity1", "check1")
+	event := corev2.FixtureEvent("entity1", "check1")
 
 	event.Check.Status = 0
 	status := messageStatus(event)
@@ -105,7 +105,7 @@ func TestMessageStatus(t *testing.T) {
 
 func TestSendMessage(t *testing.T) {
 	assert := assert.New(t)
-	event := types.FixtureEvent("entity1", "check1")
+	event := corev2.FixtureEvent("entity1", "check1")
 
 	var apiStub = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		body, _ := ioutil.ReadAll(r.Body)
@@ -129,7 +129,7 @@ func TestMain(t *testing.T) {
 		_ = os.Remove(file.Name())
 	}()
 
-	event := types.FixtureEvent("entity1", "check1")
+	event := corev2.FixtureEvent("entity1", "check1")
 	eventJSON, _ := json.Marshal(event)
 	_, err := file.WriteString(string(eventJSON))
 	require.NoError(t, err)