test: Add a test on protection message sort timestamp (#5088)

Even if `vc-request-with-auth` is received with a delay, the protection message must have the sort
timestamp equal to the Sent timestamp of `vc-request-with-auth`, otherwise subsequent chat messages
would also have greater sort timestamps and while it doesn't affect the chat itself (because Sent
timestamps are shown to a user), it affects the chat position in the chatlist because chats there
are sorted by sort timestamps of the last messages, so the user sees chats sorted out of
order. That's what happened in #5088 where a user restores the backup made before setting up a
verified chat with their contact and fetches new messages, including `vc-request-with-auth` and also
messages from other chats, after that.

src/securejoin.rs

@@ -770,10 +770,20 @@ mod tests {
     use crate::stock_str::chat_protection_enabled;
     use crate::test_utils::get_chat_msg;
     use crate::test_utils::{TestContext, TestContextManager};
-    use crate::tools::EmailAddress;
+    use crate::tools::{EmailAddress, SystemTime};
+    use std::time::Duration;
 
     #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     async fn test_setup_contact() {
+        test_setup_contact_ex(false).await
+    }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn test_setup_contact_protection_timestamp() {
+        test_setup_contact_ex(true).await
+    }
+
+    async fn test_setup_contact_ex(check_protection_timestamp: bool) {
         let mut tcm = TestContextManager::new();
         let alice = tcm.alice().await;
         let bob = tcm.bob().await;
@@ -862,6 +872,10 @@ mod tests {
         // Check Bob sent the right message.
         let sent = bob.pop_sent_msg().await;
         let msg = alice.parse_msg(&sent).await;
+        let vc_request_with_auth_ts_sent = msg
+            .get_header(HeaderDef::Date)
+            .and_then(|value| mailparse::dateparse(value).ok())
+            .unwrap();
         assert!(msg.was_encrypted());
         assert_eq!(
             msg.get_header(HeaderDef::SecureJoin).unwrap(),
@@ -885,6 +899,10 @@ mod tests {
             .unwrap();
         assert_eq!(contact_bob.is_verified(&alice.ctx).await.unwrap(), false);
 
+        if check_protection_timestamp {
+            SystemTime::shift(Duration::from_secs(3600));
+        }
+
         // Step 5+6: Alice receives vc-request-with-auth, sends vc-contact-confirm
         alice.recv_msg(&sent).await;
         assert_eq!(contact_bob.is_verified(&alice.ctx).await.unwrap(), true);
@@ -910,6 +928,9 @@ mod tests {
             assert!(msg.is_info());
             let expected_text = chat_protection_enabled(&alice).await;
             assert_eq!(msg.get_text(), expected_text);
+            if check_protection_timestamp {
+                assert_eq!(msg.timestamp_sort, vc_request_with_auth_ts_sent);
+            }
         }
 
         // Check Alice sent the right message to Bob.