refactor: No need to fail receive_imf, we can just exit normally

This way if the self-MDN isn't applied successfully, it can be received again and retried.

deltachat-rpc-client/tests/test_something.py

@@ -348,7 +348,7 @@ def test_receive_imf_failure(acfactory) -> None:
         snapshot.text == "❌ Failed to receive a message:"
         " Condition failed: `!context.get_config_bool(Config::SimulateReceiveImfError).await?`."
         f" Core version {version}."
-        " Please report this bug to delta@merlinux.eu or https://support.delta.chat/."
+        " Please report this bug to delta@merlinux.eu or https://support.delta.chat/"
     )
 
     # The failed message doesn't break the IMAP loop.

src/decrypt.rs

@@ -1,6 +1,7 @@
 //! Helper functions for decryption.
 //! The actual decryption is done in the [`crate::pgp`] module.
 
+use std::collections::HashSet;
 use std::io::Cursor;
 
 use anyhow::{Context as _, Result, bail};
@@ -18,8 +19,8 @@ use crate::chat::ChatId;
 use crate::constants::Chattype;
 use crate::contact::ContactId;
 use crate::context::Context;
-use crate::key::load_self_secret_keyring;
 use crate::key::self_fingerprint;
+use crate::key::{Fingerprint, SignedPublicKey, load_self_secret_keyring};
 use crate::token::Namespace;
 
 /// Tries to decrypt the message,
@@ -334,6 +335,36 @@ fn get_autocrypt_mime<'a, 'b>(mail: &'a ParsedMail<'b>) -> Option<&'a ParsedMail
     }
 }
 
+/// Validates signatures of Multipart/Signed message part, as defined in RFC 1847.
+///
+/// Returns the signed part and the set of key
+/// fingerprints for which there is a valid signature.
+///
+/// Returns None if the message is not Multipart/Signed or doesn't contain necessary parts.
+pub(crate) fn validate_detached_signature<'a, 'b>(
+    mail: &'a ParsedMail<'b>,
+    public_keyring_for_validate: &[SignedPublicKey],
+) -> Option<(&'a ParsedMail<'b>, HashSet<Fingerprint>)> {
+    if mail.ctype.mimetype != "multipart/signed" {
+        return None;
+    }
+
+    if let [first_part, second_part] = &mail.subparts[..] {
+        // First part is the content, second part is the signature.
+        let content = first_part.raw_bytes;
+        let ret_valid_signatures = match second_part.get_body_raw() {
+            Ok(signature) => {
+                crate::pgp::pk_validate(content, &signature, public_keyring_for_validate)
+                    .unwrap_or_default()
+            }
+            Err(_) => Default::default(),
+        };
+        Some((first_part, ret_valid_signatures))
+    } else {
+        None
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/imap.rs

@@ -1383,13 +1383,15 @@ impl Session {
                 let res = receive_imf_inner(context, rfc724_mid, body, is_seen).await;
                 let received_msg = match res {
                     Err(err) => {
-                        warn!(context, "receive_imf error: {err:#}.");
-
-                        let text = format!(
-                            "❌ Failed to receive a message: {err:#}. Core version v{DC_VERSION_STR}. Please report this bug to delta@merlinux.eu or https://support.delta.chat/.",
-                        );
-                        let mut msg = Message::new_text(text);
-                        add_device_msg(context, None, Some(&mut msg)).await?;
+                        let err = format!("{err:#}");
+                        warn!(context, "receive_imf error: {err}.");
+                        if !err.contains("(SKIP_DEVICE_MSG)") {
+                            let text = format!(
+                                "❌ Failed to receive a message: {err}. Core version v{DC_VERSION_STR}. Please report this bug to delta@merlinux.eu or https://support.delta.chat/",
+                            );
+                            let mut msg = Message::new_text(text);
+                            add_device_msg(context, None, Some(&mut msg)).await?;
+                        }
                         None
                     }
                     Ok(msg) => msg,

src/location.rs

@@ -871,7 +871,7 @@ mod tests {
     use crate::config::Config;
     use crate::message::MessageState;
     use crate::receive_imf::receive_imf;
-    use crate::test_utils::{TestContext, TestContextManager};
+    use crate::test_utils::{ExpectedEvents, TestContext, TestContextManager};
     use crate::tools::SystemTime;
 
     #[test]
@@ -1103,6 +1103,9 @@ Content-Disposition: attachment; filename="location.kml"
             .await?;
 
         let alice_chat = alice.create_chat(bob).await;
+        // Bob needs the chat accepted so that "normal" messages from Alice trigger `IncomingMsg`.
+        // Location-only messages still must trigger `MsgsChanged`.
+        bob.create_chat(alice).await;
 
         // Alice enables location streaming.
         // Bob receives a message saying that Alice enabled location streaming.
@@ -1117,7 +1120,18 @@ Content-Disposition: attachment; filename="location.kml"
         SystemTime::shift(Duration::from_secs(10));
         delete_expired(alice, time()).await?;
         maybe_send(alice).await?;
+        bob.evtracker.clear_events();
         bob.recv_msg_opt(&alice.pop_sent_msg().await).await;
+        bob.evtracker
+            .get_matching_ex(
+                bob,
+                ExpectedEvents {
+                    expected: |e| matches!(e, EventType::MsgsChanged { .. }),
+                    unexpected: |e| matches!(e, EventType::IncomingMsg { .. }),
+                },
+            )
+            .await
+            .unwrap();
         assert_eq!(get_range(alice, None, None, 0, 0).await?.len(), 1);
         assert_eq!(get_range(bob, None, None, 0, 0).await?.len(), 1);
 

src/mimeparser.rs

@@ -20,7 +20,7 @@ use crate::config::Config;
 use crate::constants;
 use crate::contact::{ContactId, import_public_key};
 use crate::context::Context;
-use crate::decrypt::{self};
+use crate::decrypt::{self, validate_detached_signature};
 use crate::dehtml::dehtml;
 use crate::download::PostMsgMetadata;
 use crate::events::EventType;
@@ -487,6 +487,17 @@ impl MimeMessage {
             HashMap::new()
         };
 
+        let mail = mail.as_ref().map(|mail| {
+            let (content, signatures_detached) = validate_detached_signature(mail, &public_keyring)
+                .unwrap_or((mail, Default::default()));
+            let signatures_detached = signatures_detached
+                .into_iter()
+                .map(|fp| (fp, Vec::new()))
+                .collect::<HashMap<_, _>>();
+            signatures.extend(signatures_detached);
+            content
+        });
+
         if let Some(expected_sender_fingerprint) = expected_sender_fingerprint {
             ensure!(
                 !signatures.is_empty(),
@@ -502,7 +513,7 @@ impl MimeMessage {
             );
         }
 
-        if let (Ok(mail), true) = (&mail, is_encrypted) {
+        if let (Ok(mail), true) = (mail, is_encrypted) {
             if !signatures.is_empty() {
                 // Unsigned "Subject" mustn't be prepended to messages shown as encrypted
                 // (<https://github.com/deltachat/deltachat-core-rust/issues/1790>).
@@ -527,7 +538,7 @@ impl MimeMessage {
                 &mut inner_from,
                 &mut list_post,
                 &mut chat_disposition_notification_to,
-                &mail,
+                mail,
             );
 
             if !signatures.is_empty() {
@@ -571,7 +582,7 @@ impl MimeMessage {
             signatures.clear();
         }
 
-        if let (Ok(mail), true) = (&mail, is_encrypted)
+        if let (Ok(mail), true) = (mail, is_encrypted)
             && let Some(post_msg_rfc724_mid) =
                 mail.headers.get_header_value(HeaderDef::ChatPostMessageId)
         {
@@ -629,7 +640,7 @@ impl MimeMessage {
             from,
             incoming,
             chat_disposition_notification_to,
-            decryption_error: mail.as_ref().err().map(|err| format!("{err:#}")),
+            decryption_error: mail.err().map(|err| format!("{err:#}")),
 
             // only non-empty if it was a valid autocrypt message
             signature,
@@ -655,9 +666,9 @@ impl MimeMessage {
             pre_message,
         };
 
-        match &mail {
+        match mail {
             Ok(mail) => {
-                parser.parse_mime_recursive(context, &mail, false).await?;
+                parser.parse_mime_recursive(context, mail, false).await?;
             }
             Err(err) => {
                 let txt = "[This message cannot be decrypted.\n\n• It might already help to simply reply to this message and ask the sender to send the message again.\n\n• If you just re-installed Delta Chat then it is best if you re-setup Delta Chat now and choose \"Add as second device\" or import a backup.]";

src/reaction.rs

@@ -18,7 +18,7 @@ use std::cmp::Ordering;
 use std::collections::BTreeMap;
 use std::fmt;
 
-use anyhow::Result;
+use anyhow::{Result, bail};
 use serde::{Deserialize, Serialize};
 
 use crate::chat::{Chat, ChatId, send_msg};
@@ -243,7 +243,7 @@ pub(crate) async fn set_msg_reaction(
     timestamp: i64,
     reaction: Reaction,
     is_incoming_fresh: bool,
-) -> Result<()> {
+) -> Result<bool> {
     if let Some(msg_id) = rfc724_mid_exists(context, in_reply_to).await? {
         set_msg_id_reaction(context, msg_id, chat_id, contact_id, timestamp, &reaction).await?;
 
@@ -258,13 +258,14 @@ pub(crate) async fn set_msg_reaction(
                 reaction,
             });
         }
+        Ok(true)
     } else {
         info!(
             context,
             "Can't assign reaction to unknown message with Message-ID {}", in_reply_to
         );
+        Ok(false)
     }
-    Ok(())
 }
 
 /// Returns a structure containing all reactions to the message.
@@ -519,6 +520,54 @@ Content-Disposition: reaction\n\
         Ok(())
     }
 
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+    async fn test_reaction_and_multitransport() -> Result<()> {
+        let mut tcm = TestContextManager::new();
+        let alice = &tcm.alice().await;
+        let device_chat_id = ChatId::get_for_contact(alice, ContactId::DEVICE).await?;
+        let n_device_msgs = get_chat_msgs(alice, device_chat_id).await?.len();
+
+        let reaction_bytes = "To: alice@example.org, claire@example.org\n\
+From: bob@example.net\n\
+Date: Today, 29 February 2021 00:00:10 -800\n\
+Message-ID: 56789@example.net\n\
+In-Reply-To: 12345@example.org\n\
+Content-Type: text/plain; charset=utf-8\n\
+Content-Disposition: reaction\n\
+\n\
+\u{1F44D}"
+            .as_bytes();
+        // Alice receives a reaction to Claire's message from Bob earler than the message itself
+        // because Bob knows about Alice's new transport.
+        receive_imf(alice, reaction_bytes, false).await?;
+
+        let msg_id = receive_imf(
+            alice,
+            "To: alice@example.org, bob@example.net\n\
+From: claire@example.org\n\
+Date: Today, 29 February 2021 00:00:00 -800\n\
+Message-ID: 12345@example.org\n\
+\n\
+Can we chat at 1pm pacific, today?"
+                .as_bytes(),
+            false,
+        )
+        .await?
+        .unwrap()
+        .msg_ids[0];
+
+        // Finally the reaction arrives on Alice's older transport.
+        receive_imf(alice, reaction_bytes, false).await?;
+        let reactions = get_msg_reactions(alice, msg_id).await?;
+        assert_eq!(reactions.to_string(), "👍1");
+
+        assert_eq!(
+            get_chat_msgs(alice, device_chat_id).await?.len(),
+            n_device_msgs
+        );
+        Ok(())
+    }
+
     async fn expect_reactions_changed_event(
         t: &TestContext,
         expected_chat_id: ChatId,

src/receive_imf.rs

@@ -6,7 +6,7 @@ use std::iter;
 use std::str::FromStr as _;
 use std::sync::LazyLock;
 
-use anyhow::{Context as _, Result, ensure};
+use anyhow::{Context as _, Result, bail, ensure};
 use deltachat_contact_tools::{
     ContactAddress, addr_cmp, addr_normalize, may_be_valid_addr, sanitize_bidi_characters,
     sanitize_single_line,
@@ -935,75 +935,6 @@ UPDATE config SET value=? WHERE keyname='configured_addr' AND value!=?1
             // This is a Delta Chat MDN. Mark as read.
             markseen_on_imap_table(context, rfc724_mid_orig).await?;
         }
-        if !mime_parser.incoming && !context.get_config_bool(Config::TeamProfile).await? {
-            let mut updated_chats = BTreeMap::new();
-            let mut archived_chats_maybe_noticed = false;
-            for report in &mime_parser.mdn_reports {
-                for msg_rfc724_mid in report
-                    .original_message_id
-                    .iter()
-                    .chain(&report.additional_message_ids)
-                {
-                    let Some(msg_id) = rfc724_mid_exists(context, msg_rfc724_mid).await? else {
-                        continue;
-                    };
-                    let Some(msg) = Message::load_from_db_optional(context, msg_id).await? else {
-                        continue;
-                    };
-                    if msg.state < MessageState::InFresh || msg.state >= MessageState::InSeen {
-                        continue;
-                    }
-                    if !mime_parser.was_encrypted() && msg.get_showpadlock() {
-                        warn!(context, "MDN: Not encrypted. Ignoring.");
-                        continue;
-                    }
-                    message::update_msg_state(context, msg_id, MessageState::InSeen).await?;
-                    if let Err(e) = msg_id.start_ephemeral_timer(context).await {
-                        error!(context, "start_ephemeral_timer for {msg_id}: {e:#}.");
-                    }
-                    if !mime_parser.has_chat_version() {
-                        continue;
-                    }
-                    archived_chats_maybe_noticed |= msg.state < MessageState::InNoticed
-                        && msg.chat_visibility == ChatVisibility::Archived;
-                    updated_chats
-                        .entry(msg.chat_id)
-                        .and_modify(|pos| *pos = cmp::max(*pos, (msg.timestamp_sort, msg.id)))
-                        .or_insert((msg.timestamp_sort, msg.id));
-                }
-            }
-            for (chat_id, (timestamp_sort, msg_id)) in updated_chats {
-                context
-                    .sql
-                    .execute(
-                        "
-UPDATE msgs SET state=? WHERE
-    state=? AND
-    hidden=0 AND
-    chat_id=? AND
-    (timestamp,id)<(?,?)",
-                        (
-                            MessageState::InNoticed,
-                            MessageState::InFresh,
-                            chat_id,
-                            timestamp_sort,
-                            msg_id,
-                        ),
-                    )
-                    .await
-                    .context("UPDATE msgs.state")?;
-                if chat_id.get_fresh_msg_cnt(context).await? == 0 {
-                    // Removes all notifications for the chat in UIs.
-                    context.emit_event(EventType::MsgsNoticed(chat_id));
-                } else {
-                    context.emit_msgs_changed_without_msg_id(chat_id);
-                }
-                chatlist_events::emit_chatlist_item_changed(context, chat_id);
-            }
-            if archived_chats_maybe_noticed {
-                context.on_archived_chats_maybe_noticed();
-            }
-        }
     }
 
     if mime_parser.is_call() {
@@ -1019,8 +950,15 @@ UPDATE msgs SET state=? WHERE
         let is_bot = context.get_config_bool(Config::Bot).await?;
         let is_pre_message = matches!(mime_parser.pre_message, PreMessageMode::Pre { .. });
         let skip_bot_notify = is_bot && is_pre_message;
-        let important =
-            mime_parser.incoming && fresh && !is_old_contact_request && !skip_bot_notify;
+        let is_empty = !is_pre_message
+            && mime_parser.parts.first().is_none_or(|p| {
+                p.typ == Viewtype::Text && p.msg.is_empty() && p.param.get(Param::Quote).is_none()
+            });
+        let important = mime_parser.incoming
+            && !is_empty
+            && fresh
+            && !is_old_contact_request
+            && !skip_bot_notify;
 
         for msg_id in &received_msg.msg_ids {
             chat_id.emit_msg_event(context, *msg_id, important);
@@ -2058,9 +1996,8 @@ async fn add_parts(
                     }
                 }
                 None => {
-                    warn!(
-                        context,
-                        "Cannot add iroh peer because WebXDC instance does not exist."
+                    bail!(
+                        "Cannot add iroh peer because WebXDC instance {in_reply_to} does not exist (SKIP_DEVICE_MSG)"
                     );
                 }
             },
@@ -2093,6 +2030,82 @@ async fn add_parts(
             warn!(context, "Call: Not a reply.")
         }
     }
+    if !mime_parser.incoming && !context.get_config_bool(Config::TeamProfile).await? {
+        let mut missing_rfc724_mid = None;
+        let mut updated_chats = BTreeMap::new();
+        let mut archived_chats_maybe_noticed = false;
+        for report in &mime_parser.mdn_reports {
+            for msg_rfc724_mid in report
+                .original_message_id
+                .iter()
+                .chain(&report.additional_message_ids)
+            {
+                let Some(msg_id) = rfc724_mid_exists(context, msg_rfc724_mid).await? else {
+                    missing_rfc724_mid.get_or_insert(msg_rfc724_mid.as_str());
+                    continue;
+                };
+                let Some(msg) = Message::load_from_db_optional(context, msg_id).await? else {
+                    continue;
+                };
+                if msg.state < MessageState::InFresh || msg.state >= MessageState::InSeen {
+                    continue;
+                }
+                if !mime_parser.was_encrypted() && msg.get_showpadlock() {
+                    warn!(context, "MDN: Not encrypted. Ignoring.");
+                    continue;
+                }
+                message::update_msg_state(context, msg_id, MessageState::InSeen).await?;
+                if let Err(e) = msg_id.start_ephemeral_timer(context).await {
+                    error!(context, "start_ephemeral_timer for {msg_id}: {e:#}.");
+                }
+                if !mime_parser.has_chat_version() {
+                    continue;
+                }
+                archived_chats_maybe_noticed |= msg.state < MessageState::InNoticed
+                    && msg.chat_visibility == ChatVisibility::Archived;
+                updated_chats
+                    .entry(msg.chat_id)
+                    .and_modify(|pos| *pos = cmp::max(*pos, (msg.timestamp_sort, msg.id)))
+                    .or_insert((msg.timestamp_sort, msg.id));
+            }
+        }
+        for (chat_id, (timestamp_sort, msg_id)) in updated_chats {
+            context
+                .sql
+                .execute(
+                    "
+UPDATE msgs SET state=? WHERE
+state=? AND
+hidden=0 AND
+chat_id=? AND
+(timestamp,id)<(?,?)",
+                    (
+                        MessageState::InNoticed,
+                        MessageState::InFresh,
+                        chat_id,
+                        timestamp_sort,
+                        msg_id,
+                    ),
+                )
+                .await
+                .context("UPDATE msgs.state")?;
+            if chat_id.get_fresh_msg_cnt(context).await? == 0 {
+                // Removes all notifications for the chat in UIs.
+                context.emit_event(EventType::MsgsNoticed(chat_id));
+            } else {
+                context.emit_msgs_changed_without_msg_id(chat_id);
+            }
+            chatlist_events::emit_chatlist_item_changed(context, chat_id);
+        }
+        if archived_chats_maybe_noticed {
+            context.on_archived_chats_maybe_noticed();
+        }
+        ensure!(
+            missing_rfc724_mid.is_none(),
+            "Self-MDN: {} not found (SKIP_DEVICE_MSG)",
+            missing_rfc724_mid.unwrap_or(""),
+        );
+    }
 
     let hidden = mime_parser.parts.iter().all(|part| part.is_reaction);
     let mut parts = mime_parser.parts.iter().peekable();
@@ -2101,7 +2114,7 @@ async fn add_parts(
         if part.is_reaction {
             let reaction_str = simplify::remove_footers(part.msg.as_str());
             let is_incoming_fresh = mime_parser.incoming && !seen;
-            set_msg_reaction(
+            if !set_msg_reaction(
                 context,
                 mime_in_reply_to,
                 chat_id,
@@ -2110,7 +2123,17 @@ async fn add_parts(
                 Reaction::new(reaction_str.as_str()),
                 is_incoming_fresh,
             )
-            .await?;
+            .await?
+            {
+                return Ok(ReceivedMsg {
+                    chat_id,
+                    state,
+                    hidden,
+                    sort_timestamp,
+                    msg_ids: vec![],
+                    needs_delete_job: false,
+                });
+            }
         }
 
         let mut param = part.param.clone();
@@ -2373,10 +2396,7 @@ async fn handle_edit_delete(
                 warn!(context, "Edit message: Database entry does not exist.");
             }
         } else {
-            warn!(
-                context,
-                "Edit message: rfc724_mid {rfc724_mid:?} not found."
-            );
+            bail!("Edit message: rfc724_mid {rfc724_mid:?} not found (SKIP_DEVICE_MSG)");
         }
     } else if let Some(rfc724_mid_list) = mime_parser.get_header(HeaderDef::ChatDelete)
         && let Some(part) = mime_parser.parts.first()

src/receive_imf/receive_imf_tests.rs

@@ -14,7 +14,9 @@ use crate::contact;
 use crate::imap::prefetch_should_download;
 use crate::imex::{ImexMode, imex};
 use crate::key;
+use crate::message::markseen_msgs;
 use crate::securejoin::get_securejoin_qr;
+use crate::smtp;
 use crate::test_utils::{
     TestContext, TestContextManager, alice_keypair, get_chat_msg, mark_as_verified,
 };
@@ -2655,6 +2657,32 @@ async fn test_read_receipts_dont_unmark_bots() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_self_mdn_before_msg() -> Result<()> {
+    let mut tcm = TestContextManager::new();
+    let alice = &tcm.alice().await;
+    let bob = &tcm.bob().await;
+    let bob2 = &tcm.bob().await;
+    let alice_chat = alice.create_chat(bob).await;
+
+    let sent = alice.send_text(alice_chat.id, "hi").await;
+    let msg = bob.recv_msg(&sent).await;
+    msg.chat_id.accept(bob).await?;
+    markseen_msgs(bob, vec![msg.id]).await?;
+    smtp::queue_mdn(bob).await?;
+    let sent_mdn = bob.pop_sent_msg().await;
+
+    let Err(err) = receive_imf(bob2, sent_mdn.payload().as_bytes(), false).await else {
+        unreachable!();
+    };
+    assert!(format!("{err:#}").contains("(SKIP_DEVICE_MSG)"));
+    let msg = bob2.recv_msg(&sent).await;
+    assert_eq!(msg.get_state(), MessageState::InFresh);
+    bob2.recv_msg_trash(&sent_mdn).await;
+    assert_eq!(msg.id.get_state(bob2).await?, MessageState::InSeen);
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn test_gmx_forwarded_msg() -> Result<()> {
     let t = TestContext::new_alice().await;

src/smtp.rs

@@ -13,7 +13,7 @@ use crate::config::Config;
 use crate::contact::{Contact, ContactId};
 use crate::context::Context;
 use crate::events::EventType;
-use crate::log::{LogExt, warn};
+use crate::log::warn;
 use crate::message::Message;
 use crate::message::{self, MsgId};
 use crate::mimefactory::MimeFactory;
@@ -590,44 +590,77 @@ async fn send_mdn_rfc724_mid(
     if context.get_config_bool(Config::BccSelf).await? {
         add_self_recipients(context, &mut recipients, encrypted).await?;
     }
-    let recipients: Vec<_> = recipients
-        .into_iter()
-        .filter_map(|addr| {
-            async_smtp::EmailAddress::new(addr.clone())
-                .with_context(|| format!("Invalid recipient: {addr}"))
-                .log_err(context)
-                .ok()
-        })
-        .collect();
+    #[cfg(not(test))]
+    {
+        use crate::log::LogExt;
 
-    match smtp_send(context, &recipients, &body, smtp, None).await {
-        SendResult::Success => {
-            if !recipients.is_empty() {
-                info!(context, "Successfully sent MDN for {rfc724_mid}.");
+        let recipients: Vec<_> = recipients
+            .into_iter()
+            .filter_map(|addr| {
+                async_smtp::EmailAddress::new(addr.clone())
+                    .with_context(|| format!("Invalid recipient: {addr}"))
+                    .log_err(context)
+                    .ok()
+            })
+            .collect();
+
+        match smtp_send(context, &recipients, &body, smtp, None).await {
+            SendResult::Success => {
+                if !recipients.is_empty() {
+                    info!(context, "Successfully sent MDN for {rfc724_mid}.");
+                }
+                context
+                    .sql
+                    .transaction(|transaction| {
+                        let mut stmt =
+                            transaction.prepare("DELETE FROM smtp_mdns WHERE rfc724_mid = ?")?;
+                        stmt.execute((rfc724_mid,))?;
+                        for additional_rfc724_mid in additional_rfc724_mids {
+                            stmt.execute((additional_rfc724_mid,))?;
+                        }
+                        Ok(())
+                    })
+                    .await?;
+                Ok(true)
             }
-            context
-                .sql
-                .transaction(|transaction| {
-                    let mut stmt =
-                        transaction.prepare("DELETE FROM smtp_mdns WHERE rfc724_mid = ?")?;
-                    stmt.execute((rfc724_mid,))?;
-                    for additional_rfc724_mid in additional_rfc724_mids {
-                        stmt.execute((additional_rfc724_mid,))?;
-                    }
-                    Ok(())
-                })
-                .await?;
-            Ok(true)
+            SendResult::Retry => {
+                info!(
+                    context,
+                    "Temporary SMTP failure while sending an MDN for {rfc724_mid}."
+                );
+                Ok(false)
+            }
+            SendResult::Failure(err) => Err(err),
         }
-        SendResult::Retry => {
-            info!(
-                context,
-                "Temporary SMTP failure while sending an MDN for {rfc724_mid}."
-            );
-            Ok(false)
-        }
-        SendResult::Failure(err) => Err(err),
     }
+    #[cfg(test)]
+    {
+        let _ = smtp;
+        context
+            .sql
+            .transaction(|t| {
+                t.execute(
+                    "INSERT INTO smtp (rfc724_mid, recipients, mime, msg_id)
+                    VALUES (?, ?, ?, ?)",
+                    (rfc724_mid, recipients.join(" "), body, u32::MAX),
+                )?;
+                let mut stmt = t.prepare("DELETE FROM smtp_mdns WHERE rfc724_mid = ?")?;
+                stmt.execute((rfc724_mid,))?;
+                for additional_rfc724_mid in additional_rfc724_mids {
+                    stmt.execute((additional_rfc724_mid,))?;
+                }
+                Ok(())
+            })
+            .await?;
+        Ok(true)
+    }
+}
+
+#[cfg(test)]
+pub(crate) async fn queue_mdn(context: &Context) -> Result<()> {
+    let queued = send_mdn(context, &mut Smtp::new()).await?;
+    assert!(queued);
+    Ok(())
 }
 
 /// Tries to send a single MDN. Returns true if more MDNs should be sent.

src/test_utils.rs

@@ -1431,6 +1431,12 @@ pub fn fiona_keypair() -> SignedSecretKey {
 #[derive(Debug)]
 pub struct EventTracker(EventEmitter);
 
+/// See [`super::EventTracker::get_matching_ex`].
+pub struct ExpectedEvents<E: Fn(&EventType) -> bool, U: Fn(&EventType) -> bool> {
+    pub expected: E,
+    pub unexpected: U,
+}
+
 impl Deref for EventTracker {
     type Target = EventEmitter;
 
@@ -1467,21 +1473,39 @@ impl EventTracker {
         .expect("timeout waiting for event match")
     }
 
-    /// Consumes emitted events returning the first matching one if any.
+    /// Consumes all emitted events returning the first matching one if any.
     pub async fn get_matching_opt<F: Fn(&EventType) -> bool>(
         &self,
         ctx: &Context,
         event_matcher: F,
+    ) -> Option<EventType> {
+        self.get_matching_ex(
+            ctx,
+            ExpectedEvents {
+                expected: event_matcher,
+                unexpected: |_| false,
+            },
+        )
+        .await
+    }
+
+    /// Consumes all emitted events returning the first matching one if any. Panics on unexpected
+    /// events.
+    pub async fn get_matching_ex<E: Fn(&EventType) -> bool, U: Fn(&EventType) -> bool>(
+        &self,
+        ctx: &Context,
+        args: ExpectedEvents<E, U>,
     ) -> Option<EventType> {
         ctx.emit_event(EventType::Test);
         let mut found_event = None;
         loop {
             let event = self.recv().await.unwrap();
+            assert!(!(args.unexpected)(&event.typ));
             if let EventType::Test = event.typ {
                 return found_event;
             }
-            if event_matcher(&event.typ) {
-                found_event = Some(event.typ);
+            if (args.expected)(&event.typ) {
+                found_event.get_or_insert(event.typ);
             }
         }
     }