Added LinkPreview feature (#467)

* Added LinkPreview feature

Posts will randomly contain links now.

Also made it part of the deployment config.

* Tune percent chance of link

deployment/terraform/create.go

@@ -379,6 +379,7 @@ func (t *Terraform) updateAppConfig(ip string, sshc *ssh.Client, jobServerEnable
 	cfg.ServiceSettings.IdleTimeout = model.NewInt(90)
 	cfg.ServiceSettings.EnableLocalMode = model.NewBool(true)
 	cfg.ServiceSettings.CollapsedThreads = model.NewString(model.CollapsedThreadsDefaultOn)
+	cfg.ServiceSettings.EnableLinkPreviews = model.NewBool(true)
 	cfg.EmailSettings.SMTPServer = model.NewString(t.output.MetricsServer.PrivateIP)
 	cfg.EmailSettings.SMTPPort = model.NewString("2500")
 

loadtest/control/simulcontroller/actions.go

@@ -870,6 +870,12 @@ func createMessage(u user.User, channel *model.Channel, isReply bool) (string, e
 		}
 		message = "@" + user.Username + " "
 	}
+
+	// 10% of messages will contain a link.
+	if rand.Float64() < 0.10 {
+		message = control.AddLink(message)
+	}
+
 	message += genMessage(isReply)
 	return message, nil
 }

loadtest/control/utils.go

@@ -43,6 +43,15 @@ var (
 	words             = []string{}
 	emojis            = []string{":grinning:", ":slightly_smiling_face:", ":smile:", ":sunglasses:"}
 	serverVersionRE   = regexp.MustCompile(`\d+.\d+\.\d+`)
+	links             = []string{
+		"https://github.com/mattermost/mattermost-server",
+		"https://www.youtube.com/watch?v=-5jompL6G-k",
+		"https://www.youtube.com/watch?v=GKLyAVHgNzY",
+		"https://mattermost.com",
+		"https://developers.mattermost.com",
+		"https://golang.org",
+		"https://reactjs.org",
+	}
 )
 
 // getErrOrigin returns a string indicating the location of the error that
@@ -138,6 +147,14 @@ func GenerateRandomSentences(count int) string {
 	return random[:len(random)-1] + "."
 }
 
+// AddLink appends a link to a string to test the LinkPreview feature.
+func AddLink(input string) string {
+	n := rand.Int() % len(links)
+	link := links[n]
+
+	return input + " " + link + " "
+}
+
 // SelectWeighted does a random weighted selection on a given slice of weights.
 func SelectWeighted(weights []int) (int, error) {
 	var sum int

loadtest/control/utils_test.go

@@ -87,6 +87,14 @@ func TestGenerateRandomSentences(t *testing.T) {
 	require.Equal(t, s[0], "🙂")
 }
 
+func TestAddLink(t *testing.T) {
+	msg := "hello world"
+	out := AddLink(msg)
+	words := strings.Split(out, " ")
+	require.Len(t, words, 4)
+	assert.Contains(t, links, words[2])
+}
+
 func TestSelectWeighted(t *testing.T) {
 	t.Run("empty weights", func(t *testing.T) {
 		idx, err := SelectWeighted([]int{})