[FIX] mail, im_livechat: make livechat work properly

- fix traceback on receiving first livechat message due to bad computation of
  correspondent
- fix missing [0] in return of country name_get in channel_info
- fix visitor/correspondent computation to work when chatting with oneself
- reintroduce livechat ordered by last message in discuss sidebar
- improve mock server to make these fixes possible to test
- introduce corresponding tests

PR: #56243
task-2323670

closes odoo/odoo#56414

X-original-commit: f623bfd2c8819604c709bc723153c071dca6e3cc
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/addons/mail/static/src/models/thread/thread.js b/addons/mail/static/src/models/thread/thread.js
index 74cae5d25ab..e3d48d54e35 100644
--- a/addons/mail/static/src/models/thread/thread.js
+++ b/addons/mail/static/src/models/thread/thread.js
@@ -779,8 +779,13 @@ function factory(dependencies) {
                 partner !== this.env.messaging.currentPartner
             );
             if (correspondents.length === 1) {
+                // 2 members chat
                 return [['link', correspondents[0]]];
             }
+            if (this.members.length === 1) {
+                // chat with oneself
+                return [['link', this.members[0]]];
+            }
             return [['unlink']];
         }
 
@@ -1360,6 +1365,13 @@ function factory(dependencies) {
         messages: many2many('mail.message', {
             inverse: 'threads',
         }),
+        /**
+         * All messages that are contained on this channel on the server.
+         * Equivalent to the inverse of python field `channel_ids`.
+         */
+        messagesAsServerChannel: many2many('mail.message', {
+            inverse: 'serverChannels',
+        }),
         messageSeenIndicators: one2many('mail.message_seen_indicator', {
             inverse: 'thread',
             isCausal: true,