Fix test_leave_group, make it possible to leave the group

Author: link2xt

src/chat.rs

@@ -2859,19 +2859,26 @@ async fn prepare_send_msg(
 ) -> Result<Vec<i64>> {
     let mut chat = Chat::load_from_db(context, chat_id).await?;
 
-    // Check if the chat can be sent to.
-    if let Some(reason) = chat.why_cant_send(context).await? {
-        if matches!(
-            reason,
-            CantSendReason::ProtectionBroken
-                | CantSendReason::ContactRequest
-                | CantSendReason::SecurejoinWait
-        ) && msg.param.get_cmd() == SystemMessage::SecurejoinMessage
-        {
-            // Send out the message, the securejoin message is supposed to repair the verification.
-            // If the chat is a contact request, let the user accept it later.
-        } else {
-            bail!("cannot send to {chat_id}: {reason}");
+    // Check if the chat can be sent to,
+    // but always allow to send "Member removed" messages
+    // so we can leave the group.
+    //
+    // Necessary checks should be made anyway before removing contact
+    // from the chat.
+    if msg.param.get_cmd() != SystemMessage::MemberRemovedFromGroup {
+        if let Some(reason) = chat.why_cant_send(context).await? {
+            if matches!(
+                reason,
+                CantSendReason::ProtectionBroken
+                    | CantSendReason::ContactRequest
+                    | CantSendReason::SecurejoinWait
+            ) && msg.param.get_cmd() == SystemMessage::SecurejoinMessage
+            {
+                // Send out the message, the securejoin message is supposed to repair the verification.
+                // If the chat is a contact request, let the user accept it later.
+            } else {
+                bail!("cannot send to {chat_id}: {reason}");
+            }
         }
     }
 
@@ -3930,6 +3937,11 @@ pub async fn remove_contact_from_chat(
             bail!("{}", err_msg);
         } else {
             let mut sync = Nosync;
+
+            // Remove contact locally first
+            // to set `chats_contacts.remove_timestamp`.
+            remove_from_chat_contacts_table(context, chat_id, contact_id).await?;
+
             // We do not return an error if the contact does not exist in the database.
             // This allows to delete dangling references to deleted contacts
             // in case of the database becoming inconsistent due to a bug.
@@ -3959,18 +3971,6 @@ pub async fn remove_contact_from_chat(
                     sync = Sync;
                 }
             }
-            // we remove the member from the chat after constructing the
-            // to-be-send message. If between send_msg() and here the
-            // process dies, the user will be able to redo the action. It's better than the other
-            // way round: you removed someone from DB but no peer or device gets to know about it
-            // and group membership is thus different on different devices. But if send_msg()
-            // failed, we still remove the member locally, otherwise it would be impossible to
-            // remove a member with missing key from a protected group.
-            // Note also that sending a message needs all recipients
-            // in order to correctly determine encryption so if we
-            // removed it first, it would complicate the
-            // check/encryption logic.
-            remove_from_chat_contacts_table(context, chat_id, contact_id).await?;
             context.emit_event(EventType::ChatModified(chat_id));
             if sync.into() {
                 chat.sync_contacts(context).await.log_err(context).ok();