Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/app/slack_test.go

@@ -0,0 +1,86 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package app
+
+import (
+	"testing"
+
+	"github.com/mattermost/mattermost-server/v6/model"
+)
+
+func TestProcessSlackText(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+
+	if th.App.ProcessSlackText("<!channel> foo <!channel>") != "@channel foo @channel" {
+		t.Fail()
+	}
+
+	if th.App.ProcessSlackText("<!here> bar <!here>") != "@here bar @here" {
+		t.Fail()
+	}
+
+	if th.App.ProcessSlackText("<!all> bar <!all>") != "@all bar @all" {
+		t.Fail()
+	}
+
+	userID := th.BasicUser.Id
+	username := th.BasicUser.Username
+	if th.App.ProcessSlackText("<@"+userID+"> hello") != "@"+username+" hello" {
+		t.Fail()
+	}
+}
+
+func TestProcessSlackAnnouncement(t *testing.T) {
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+
+	userID := th.BasicUser.Id
+	username := th.BasicUser.Username
+
+	attachments := []*model.SlackAttachment{
+		{
+			Pretext: "<!channel> pretext <!here>",
+			Text:    "<!channel> text <!here>",
+			Title:   "<!channel> title <!here>",
+			Fields: []*model.SlackAttachmentField{
+				{
+					Title: "foo",
+					Value: "<!channel> bar <!here>",
+					Short: true,
+				},
+			},
+		},
+		{
+			Pretext: "<@" + userID + "> pretext",
+			Text:    "<@" + userID + "> text",
+			Title:   "<@" + userID + "> title",
+			Fields: []*model.SlackAttachmentField{
+				{
+					Title: "foo",
+					Value: "<@" + userID + "> bar",
+					Short: true,
+				},
+			},
+		},
+	}
+	attachments = th.App.ProcessSlackAttachments(attachments)
+	if len(attachments) != 2 || len(attachments[0].Fields) != 1 || len(attachments[1].Fields) != 1 {
+		t.Fail()
+	}
+
+	if attachments[0].Pretext != "@channel pretext @here" ||
+		attachments[0].Text != "@channel text @here" ||
+		attachments[0].Title != "@channel title @here" ||
+		attachments[0].Fields[0].Value != "@channel bar @here" {
+		t.Fail()
+	}
+
+	if attachments[1].Pretext != "@"+username+" pretext" ||
+		attachments[1].Text != "@"+username+" text" ||
+		attachments[1].Title != "@"+username+" title" ||
+		attachments[1].Fields[0].Value != "@"+username+" bar" {
+		t.Fail()
+	}
+}