PLT-8350 "mention" when channel user count equals to max allowed num (#7976)

app/notification.go

@@ -935,7 +935,7 @@ func (a *App) GetMentionKeywordsInChannel(profiles map[string]*model.User, lookF
 
 		// Add @channel and @all to keywords if user has them turned on
 		if lookForSpecialMentions {
-			if int64(len(profiles)) < *a.Config().TeamSettings.MaxNotificationsPerChannel && profile.NotifyProps["channel"] == "true" {
+			if int64(len(profiles)) <= *a.Config().TeamSettings.MaxNotificationsPerChannel && profile.NotifyProps["channel"] == "true" {
 				keywords["@channel"] = append(keywords["@channel"], profile.Id)
 				keywords["@all"] = append(keywords["@all"], profile.Id)
 

app/notification_test.go

@@ -544,7 +544,8 @@ func TestGetMentionKeywords(t *testing.T) {
 		return duplicate_frequency
 	}
 
-	// multiple users
+	// multiple users but no more than MaxNotificationsPerChannel
+	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.TeamSettings.MaxNotificationsPerChannel = 4 })
 	profiles = map[string]*model.User{
 		user1.Id: user1,
 		user2.Id: user2,
@@ -568,6 +569,19 @@ func TestGetMentionKeywords(t *testing.T) {
 		t.Fatal("should've mentioned user3 and user4 with @all")
 	}
 
+	// multiple users and more than MaxNotificationsPerChannel
+	th.App.UpdateConfig(func(cfg *model.Config) { *cfg.TeamSettings.MaxNotificationsPerChannel = 3 })
+	mentions = th.App.GetMentionKeywordsInChannel(profiles, true)
+	if len(mentions) != 4 {
+		t.Fatal("should've returned four mention keywords")
+	} else if _, ok := mentions["@channel"]; ok {
+		t.Fatal("should not have mentioned any user with @channel")
+	} else if _, ok := mentions["@all"]; ok {
+		t.Fatal("should not have mentioned any user with @all")
+	} else if _, ok := mentions["@here"]; ok {
+		t.Fatal("should not have mentioned any user with @here")
+	}
+
 	// no special mentions
 	profiles = map[string]*model.User{
 		user1.Id: user1,