PLT-3077 Add group messaging (#5489)

* Implement server changes for group messaging

* Majority of client-side implementation

* Some server updates

* Added new React multiselect component

* Fix style issues

* Add custom renderer for options

* Fix model test

* Update ENTER functionality for multiselect control

* Remove buttons from multiselect UI control

* Updating group messaging UI (#5524)

* Move filter controls up a component level

* Scroll with arrow keys

* Updating mobile layout for multiselect (#5534)

* Fix race condition when backspacing quickly

* Hidden or new GMs show up for regular messages

* Add overriding of number remaining text

* Add UI filtering for team if config setting set

* Add icon to channel switcher and class prop to status icon

* Minor updates per feedback

* Improving group messaging UI (#5563)

* UX changes per feedback

* Update email for group messages

* UI fixes for group messaging (#5587)

* Fix missing localization string

* Add maximum users message when adding members to GM

* Fix input clearing on Android

* Updating group messaging UI (#5603)

* Updating UI for group messaging (#5604)

model/channel_test.go

@@ -104,3 +104,24 @@ func TestChannelPreUpdate(t *testing.T) {
 	o := Channel{Name: "test"}
 	o.PreUpdate()
 }
+
+func TestGetGroupDisplayNameFromUsers(t *testing.T) {
+	users := make([]*User, 4)
+	users[0] = &User{Username: NewId()}
+	users[1] = &User{Username: NewId()}
+	users[2] = &User{Username: NewId()}
+	users[3] = &User{Username: NewId()}
+
+	name := GetGroupDisplayNameFromUsers(users, true)
+	if len(name) > CHANNEL_NAME_MAX_LENGTH {
+		t.Fatal("name too long")
+	}
+}
+
+func TestGetGroupNameFromUserIds(t *testing.T) {
+	name := GetGroupNameFromUserIds([]string{NewId(), NewId(), NewId(), NewId(), NewId()})
+
+	if len(name) > CHANNEL_NAME_MAX_LENGTH {
+		t.Fatal("name too long")
+	}
+}