[MM-53057] Disallow malformed channel names for DMs (#24404)

server/channels/store/searchtest/helper.go

@@ -275,10 +275,10 @@ func (th *SearchTestHelper) createChannel(teamID, name, displayName, purpose str
 	return channel, nil
 }
 
-func (th *SearchTestHelper) createDirectChannel(teamID, name, displayName string, users []*model.User) (*model.Channel, error) {
+func (th *SearchTestHelper) createDirectChannel(teamID, displayName string, users []*model.User) (*model.Channel, error) {
 	channel := &model.Channel{
 		TeamId:      teamID,
-		Name:        name,
+		Name:        model.GetDMNameFromIds(users[0].Id, users[1].Id),
 		DisplayName: displayName,
 		Type:        model.ChannelTypeDirect,
 	}
@@ -290,7 +290,7 @@ func (th *SearchTestHelper) createDirectChannel(teamID, name, displayName string
 
 	m2 := &model.ChannelMember{}
 	m2.ChannelId = channel.Id
-	m2.UserId = users[0].Id
+	m2.UserId = users[1].Id
 	m2.NotifyProps = model.GetDefaultChannelNotifyProps()
 
 	channel, err := th.Store.Channel().SaveDirectChannel(channel, m1, m2)