fix: Move Chat-Group-Avatar to hidden headers

This is already done for Chat-User-Avatar. No changes needed on the receiver side, it already parses
Chat-Group-Avatar from hidden headers.

src/mimefactory.rs

@@ -870,6 +870,7 @@ impl MimeFactory {
                 unprotected_headers.push(header.clone());
                 hidden_headers.push(header.clone());
             } else if header_name == "chat-user-avatar"
+                || header_name == "chat-group-avatar"
                 || header_name == "chat-delete"
                 || header_name == "chat-edit"
             {

src/mimefactory/mimefactory_tests.rs

@@ -5,7 +5,7 @@ use std::str;
 
 use super::*;
 use crate::chat::{
-    add_contact_to_chat, create_group_chat, remove_contact_from_chat, send_text_msg, ChatId,
+    self, add_contact_to_chat, create_group_chat, remove_contact_from_chat, send_text_msg, ChatId,
     ProtectionStatus,
 };
 use crate::chatlist::Chatlist;
@@ -622,6 +622,43 @@ async fn test_selfavatar_unencrypted() -> anyhow::Result<()> {
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_group_avatar_unencrypted() -> anyhow::Result<()> {
+    let t = &TestContext::new_alice().await;
+    let group_id = chat::create_group_chat(t, chat::ProtectionStatus::Unprotected, "Group")
+        .await
+        .unwrap();
+    let bob = Contact::create(t, "", "bob@example.org").await?;
+    chat::add_contact_to_chat(t, group_id, bob).await?;
+
+    let file = t.dir.path().join("avatar.png");
+    let bytes = include_bytes!("../../test-data/image/avatar64x64.png");
+    tokio::fs::write(&file, bytes).await?;
+    chat::set_chat_profile_image(t, group_id, file.to_str().unwrap()).await?;
+
+    // Send message to bob: that should get multipart/mixed because of the avatar moved to inner header.
+    let mut msg = Message::new_text("this is the text!".to_string());
+    let sent_msg = t.send_msg(group_id, &mut msg).await;
+    let mut payload = sent_msg.payload().splitn(3, "\r\n\r\n");
+
+    let outer = payload.next().unwrap();
+    let inner = payload.next().unwrap();
+    let body = payload.next().unwrap();
+
+    assert_eq!(outer.match_indices("multipart/mixed").count(), 1);
+    assert_eq!(outer.match_indices("Message-ID:").count(), 1);
+    assert_eq!(outer.match_indices("Subject:").count(), 1);
+    assert_eq!(outer.match_indices("Autocrypt:").count(), 1);
+    assert_eq!(outer.match_indices("Chat-Group-Avatar:").count(), 0);
+
+    assert_eq!(inner.match_indices("text/plain").count(), 1);
+    assert_eq!(inner.match_indices("Message-ID:").count(), 1);
+    assert_eq!(inner.match_indices("Chat-Group-Avatar:").count(), 1);
+
+    assert_eq!(body.match_indices("this is the text!").count(), 1);
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn test_selfavatar_unencrypted_signed() {
     // create chat with bob, set selfavatar