save subject for messages (#2274)

save subject for messages:

- new api `dc_msg_get_subject()`,

- when quoting, use the subject of the quoted message as the new subject, instead of the
last subject in the chat

CHANGELOG.md

@@ -5,6 +5,11 @@
 - breaking change: You have to call dc_stop_io()/dc_start_io() before/after EXPORT_BACKUP:
   fix race condition and db corruption when a message was received during backup #2253
 
+- save subject for messages:
+  new api `dc_msg_get_subject()`,
+  when quoting, use the subject of the quoted message as the new subject, instead of the
+  last subject in the chat
+
 - new apis to get full or html message,
   `dc_msg_has_html()` and `dc_get_msg_html()` #2125 #2151
 

deltachat-ffi/deltachat.h

@@ -1498,6 +1498,8 @@ char*           dc_get_msg_info              (dc_context_t* context, uint32_t ms
  * this removes the need for the UI
  * to deal with different formatting options of PLAIN-parts.
  *
+ * As the title of the full-message-view, you can use the subject (see dc_msg_get_subject()).
+ *
  * **Note:** The returned HTML-code may contain scripts,
  * external images that may be misused as hidden read-receipts and so on.
  * Taking care of these parts
@@ -3344,6 +3346,25 @@ int64_t          dc_msg_get_sort_timestamp     (const dc_msg_t* msg);
 char*           dc_msg_get_text               (const dc_msg_t* msg);
 
 
+/**
+ * Get the subject of the email.
+ * If there is no subject associated with the message, an empty string is returned.
+ * NULL is never returned.
+ *
+ * You usually don't need this; if the core thinks that the subject might contain important
+ * information, it automatically prepends it to the message text.
+ *
+ * This function was introduced so that you can use the subject as the title for the 
+ * full-message-view (see dc_get_msg_html()).
+ *
+ * For outgoing messages, the subject is not stored and an empty string is returned.
+ *
+ * @memberof dc_msg_t
+ * @param msg The message object.
+ * @return The subject. The result must be released using dc_str_unref(). Never returns NULL.
+ */
+char*           dc_msg_get_subject            (const dc_msg_t* msg);
+
 /**
  * Find out full path, file name and extension of the file associated with a
  * message.

deltachat-ffi/src/lib.rs

@@ -2698,6 +2698,16 @@ pub unsafe extern "C" fn dc_msg_get_text(msg: *mut dc_msg_t) -> *mut libc::c_cha
     ffi_msg.message.get_text().unwrap_or_default().strdup()
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_msg_get_subject(msg: *mut dc_msg_t) -> *mut libc::c_char {
+    if msg.is_null() {
+        eprintln!("ignoring careless call to dc_msg_get_subject()");
+        return "".strdup();
+    }
+    let ffi_msg = &*msg;
+    ffi_msg.message.get_subject().strdup()
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_msg_get_file(msg: *mut dc_msg_t) -> *mut libc::c_char {
     if msg.is_null() {

python/tests/test_account.py

@@ -1507,7 +1507,6 @@ class TestOnlineAccount:
             messages = chat2.get_messages()
             assert len(messages) == 2
             assert messages[0].text == "msg1"
-            lp.sec("dbg file"+messages[1].filename)
             assert messages[1].filemime == "image/png"
             assert os.stat(messages[1].filename).st_size == os.stat(original_image_path).st_size
             ac.set_config("displayname", "new displayname")

src/dc_receive_imf.rs

@@ -912,10 +912,10 @@ async fn add_parts(
                 let mut stmt = conn.prepare_cached(
                     "INSERT INTO msgs \
          (rfc724_mid, server_folder, server_uid, chat_id, from_id, to_id, timestamp, \
-         timestamp_sent, timestamp_rcvd, type, state, msgrmsg,  txt, txt_raw, param, \
+         timestamp_sent, timestamp_rcvd, type, state, msgrmsg,  txt, subject, txt_raw, param, \
          bytes, hidden, mime_headers,  mime_in_reply_to, mime_references, mime_modified, \
          error, ephemeral_timer, ephemeral_timestamp) \
-         VALUES (?,?,?,?,?,?,?, ?,?,?,?,?,?,?,?, ?,?,?,?,?,?, ?,?,?);",
+         VALUES (?,?,?,?,?,?,?, ?,?,?,?,?,?,?,?,?, ?,?,?,?,?,?, ?,?,?);",
                 )?;
 
                 let is_location_kml = location_kml_is
@@ -972,6 +972,7 @@ async fn add_parts(
                     state,
                     is_dc_message,
                     if trash { "" } else { &part.msg },
+                    if trash { "" } else { &subject },
                     // txt_raw might contain invalid utf8
                     if trash { "" } else { &txt_raw },
                     if trash {

src/ephemeral.rs

@@ -311,7 +311,7 @@ pub(crate) async fn delete_expired_messages(context: &Context) -> Result<bool, E
             // If you change which information is removed here, also change MsgId::trash() and
             // which information dc_receive_imf::add_parts() still adds to the db if the chat_id is TRASH
             "UPDATE msgs \
-             SET chat_id=?, txt='', txt_raw='', mime_headers='', from_id=0, to_id=0, param='' \
+             SET chat_id=?, txt='', subject='', txt_raw='', mime_headers='', from_id=0, to_id=0, param='' \
              WHERE \
              ephemeral_timestamp != 0 \
              AND ephemeral_timestamp <= ? \

src/message.rs

@@ -158,7 +158,7 @@ impl MsgId {
             .execute(
                 // If you change which information is removed here, also change delete_expired_messages() and
                 // which information dc_receive_imf::add_parts() still adds to the db if the chat_id is TRASH
-                "UPDATE msgs SET chat_id=?, txt='', txt_raw='', mime_headers='', from_id=0, to_id=0, param='' WHERE id=?",
+                "UPDATE msgs SET chat_id=?, txt='', subject='', txt_raw='', mime_headers='', from_id=0, to_id=0, param='' WHERE id=?",
                 paramsv![chat_id, self],
             )
             .await?;
@@ -307,6 +307,8 @@ pub struct Message {
     pub(crate) ephemeral_timer: EphemeralTimer,
     pub(crate) ephemeral_timestamp: i64,
     pub(crate) text: Option<String>,
+    /// The value of the Subject header. Not set for messages that we sent ourselves.
+    pub(crate) subject: String,
     pub(crate) rfc724_mid: String,
     pub(crate) in_reply_to: Option<String>,
     pub(crate) server_folder: Option<String>,
@@ -356,6 +358,7 @@ impl Message {
                     "    m.msgrmsg AS msgrmsg,",
                     "    m.mime_modified AS mime_modified,",
                     "    m.txt AS txt,",
+                    "    m.subject AS subject,",
                     "    m.param AS param,",
                     "    m.hidden AS hidden,",
                     "    m.location_id AS location,",
@@ -405,6 +408,7 @@ impl Message {
                         is_dc_message: row.get("msgrmsg")?,
                         mime_modified: row.get("mime_modified")?,
                         text: Some(text),
+                        subject: row.get("subject")?,
                         param: row.get::<_, String>("param")?.parse().unwrap_or_default(),
                         hidden: row.get("hidden")?,
                         location_id: row.get("location")?,
@@ -550,6 +554,10 @@ impl Message {
             .map(|text| dc_truncate(text, DC_MAX_GET_TEXT_LEN).to_string())
     }
 
+    pub fn get_subject(&self) -> &str {
+        &self.subject
+    }
+
     pub fn get_filename(&self) -> Option<String> {
         self.param
             .get(Param::File)
@@ -2150,7 +2158,7 @@ mod tests {
                 *mvbox_move,
                 *chat_msg,
                 if folder == &"Spam" { "INBOX" } else { folder }, // Never move setup messages, except if they are in "Spam"
-                true,
+                false,
                 true,
                 true,
                 false,

src/mimefactory.rs

@@ -1,13 +1,10 @@
-use anyhow::{bail, ensure, format_err, Error};
-use chrono::TimeZone;
-use lettre_email::{mime, Address, Header, MimeMultipartType, PartBuilder};
-
 use crate::blob::BlobObject;
 use crate::chat::{self, Chat};
 use crate::config::Config;
 use crate::constants::{Chattype, Viewtype, DC_FROM_HANDSHAKE};
 use crate::contact::Contact;
 use crate::context::{get_version_str, Context};
+use crate::dc_tools::IsNoneOrEmpty;
 use crate::dc_tools::{
     dc_create_outgoing_rfc724_mid, dc_create_smeared_timestamp, dc_get_filebytes, time,
 };
@@ -22,6 +19,10 @@ use crate::param::Param;
 use crate::peerstate::{Peerstate, PeerstateVerifiedStatus};
 use crate::simplify::escape_message_footer_marks;
 use crate::stock_str;
+use anyhow::Context as _;
+use anyhow::{bail, ensure, format_err, Error};
+use chrono::TimeZone;
+use lettre_email::{mime, Address, Header, MimeMultipartType, PartBuilder};
 use std::convert::TryInto;
 
 // attachments of 25 mb brutto should work on the majority of providers
@@ -64,6 +65,7 @@ pub struct MimeFactory<'a> {
     req_mdn: bool,
     last_added_location_id: u32,
     attach_selfavatar: bool,
+    quoted_msg_subject: Option<String>,
 }
 
 /// Result of rendering a message, ready to be submitted to a send job.
@@ -153,7 +155,8 @@ impl<'a> MimeFactory<'a> {
                     ))
                 },
             )
-            .await?;
+            .await
+            .context("Can't get mime_in_reply_to, mime_references")?;
 
         let default_str = stock_str::status_line(context).await;
         let factory = MimeFactory {
@@ -173,6 +176,7 @@ impl<'a> MimeFactory<'a> {
             req_mdn,
             last_added_location_id: 0,
             attach_selfavatar,
+            quoted_msg_subject: msg.quoted_message(context).await?.map(|m| m.subject),
         };
         Ok(factory)
     }
@@ -217,6 +221,7 @@ impl<'a> MimeFactory<'a> {
             req_mdn: false,
             last_added_location_id: 0,
             attach_selfavatar: false,
+            quoted_msg_subject: None,
         };
 
         Ok(res)
@@ -350,54 +355,64 @@ impl<'a> MimeFactory<'a> {
         }
     }
 
-    async fn subject_str(&self, context: &Context) -> String {
+    async fn subject_str(&self, context: &Context) -> anyhow::Result<String> {
-        match self.loaded {
+        Ok(match self.loaded {
             Loaded::Message { ref chat } => {
                 if self.msg.param.get_cmd() == SystemMessage::AutocryptSetupMessage {
-                    stock_str::ac_setup_msg_subject(context).await
+                    return Ok(stock_str::ac_setup_msg_subject(context).await);
-                } else if chat.typ == Chattype::Group {
+                }
+
+                if chat.typ == Chattype::Group && self.quoted_msg_subject.is_none_or_empty() {
+                    // If we have a `quoted_msg_subject`, we use the subject of the quoted message
+                    // instead of the group name
                     let re = if self.in_reply_to.is_empty() {
                         ""
                     } else {
                         "Re: "
                     };
-                    format!("{}{}", re, chat.name)
+                    return Ok(format!("{}{}", re, chat.name));
-                } else {
+                }
-                    match chat.param.get(Param::LastSubject) {
-                        Some(last_subject) => {
-                            let subject_start = if last_subject.starts_with("Chat:") {
-                                0
-                            } else {
-                                // "Antw:" is the longest abbreviation in
-                                // https://en.wikipedia.org/wiki/List_of_email_subject_abbreviations#Abbreviations_in_other_languages,
-                                // so look at the first _5_ characters:
-                                match last_subject.chars().take(5).position(|c| c == ':') {
-                                    Some(prefix_end) => prefix_end + 1,
-                                    None => 0,
-                                }
-                            };
-                            format!(
-                                "Re: {}",
-                                last_subject
-                                    .chars()
-                                    .skip(subject_start)
-                                    .collect::<String>()
-                                    .trim()
-                            )
-                        }
-                        None => {
-                            let self_name = match context.get_config(Config::Displayname).await {
-                                Some(name) => name,
-                                None => context.get_config(Config::Addr).await.unwrap_or_default(),
-                            };
 
-                            stock_str::subject_for_new_contact(context, self_name).await
+                let parent_subject = if self.quoted_msg_subject.is_none_or_empty() {
-                        }
+                    chat.param.get(Param::LastSubject)
+                } else {
+                    self.quoted_msg_subject.as_deref()
+                };
+
+                match parent_subject {
+                    Some(last_subject) => {
+                        let subject_start = if last_subject.starts_with("Chat:") {
+                            0
+                        } else {
+                            // "Antw:" is the longest abbreviation in
+                            // https://en.wikipedia.org/wiki/List_of_email_subject_abbreviations#Abbreviations_in_other_languages,
+                            // so look at the first _5_ characters:
+                            match last_subject.chars().take(5).position(|c| c == ':') {
+                                Some(prefix_end) => prefix_end + 1,
+                                None => 0,
+                            }
+                        };
+                        format!(
+                            "Re: {}",
+                            last_subject
+                                .chars()
+                                .skip(subject_start)
+                                .collect::<String>()
+                                .trim()
+                        )
+                    }
+                    None => {
+                        let self_name = match context.get_config(Config::Displayname).await {
+                            Some(name) => name,
+                            None => context.get_config(Config::Addr).await.unwrap_or_default(),
+                        };
+
+                        stock_str::subject_for_new_contact(context, self_name).await
                     }
                 }
             }
             Loaded::MDN { .. } => stock_str::read_rcpt(context).await,
-        }
+        })
     }
 
     pub fn recipients(&self) -> Vec<String> {
@@ -478,7 +493,7 @@ impl<'a> MimeFactory<'a> {
         let grpimage = self.grpimage();
         let force_plaintext = self.should_force_plaintext();
         let skip_autocrypt = self.should_skip_autocrypt();
-        let subject_str = self.subject_str(context).await;
+        let subject_str = self.subject_str(context).await?;
         let e2ee_guaranteed = self.is_e2ee_guaranteed();
         let encrypt_helper = EncryptHelper::new(context).await?;
 
@@ -1283,11 +1298,15 @@ fn maybe_encode_words(words: &str) -> String {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::chatlist::Chatlist;
+    use crate::chat::ChatId;
+
     use crate::contact::Origin;
     use crate::dc_receive_imf::dc_receive_imf;
     use crate::mimeparser::MimeMessage;
     use crate::test_utils::TestContext;
+    use crate::{chatlist::Chatlist, test_utils::get_chat_msg};
+
+    use pretty_assertions::assert_eq;
 
     #[test]
     fn test_render_email_address() {
@@ -1379,8 +1398,8 @@ mod tests {
     }
 
     #[async_std::test]
-    async fn test_subject() {
+    async fn test_subject_from_mua() {
-        // 1.: Receive a mail from an MUA or Delta Chat
+        // 1.: Receive a mail from an MUA
         assert_eq!(
             msg_to_subject_str(
                 b"Received: (Postfix, from userid 1000); Mon, 4 Dec 2006 14:51:39 +0100 (CET)\n\
@@ -1410,12 +1429,15 @@ mod tests {
             .await,
             "Re: Infos: 42"
         );
+    }
 
-        // 2. Receive a message from Delta Chat when we did not send any messages before
+    #[async_std::test]
+    async fn test_subject_from_dc() {
+        // 2. Receive a message from Delta Chat
         assert_eq!(
             msg_to_subject_str(
                 b"Received: (Postfix, from userid 1000); Mon, 4 Dec 2006 14:51:39 +0100 (CET)\n\
-                From: Charlie <charlie@example.com>\n\
+                From: bob@example.com\n\
                 To: alice@example.com\n\
                 Subject: Chat: hello\n\
                 Chat-Version: 1.0\n\
@@ -1427,7 +1449,10 @@ mod tests {
             .await,
             "Re: Chat: hello"
         );
+    }
 
+    #[async_std::test]
+    async fn test_subject_outgoing() {
         // 3. Send the first message to a new contact
         let t = TestContext::new_alice().await;
 
@@ -1438,11 +1463,14 @@ mod tests {
             .await
             .unwrap();
         assert_eq!(first_subject_str(t).await, "Message from Alice");
+    }
 
+    #[async_std::test]
+    async fn test_subject_unicode() {
         // 4. Receive messages with unicode characters and make sure that we do not panic (we do not care about the result)
         msg_to_subject_str(
             "Received: (Postfix, from userid 1000); Mon, 4 Dec 2006 14:51:39 +0100 (CET)\n\
-            From: Charlie <charlie@example.com>\n\
+            From: bob@example.com\n\
             To: alice@example.com\n\
             Subject: äääää\n\
             Chat-Version: 1.0\n\
@@ -1456,7 +1484,7 @@ mod tests {
 
         msg_to_subject_str(
             "Received: (Postfix, from userid 1000); Mon, 4 Dec 2006 14:51:39 +0100 (CET)\n\
-            From: Charlie <charlie@example.com>\n\
+            From: bob@example.com\n\
             To: alice@example.com\n\
             Subject: aäääää\n\
             Chat-Version: 1.0\n\
@@ -1467,15 +1495,18 @@ mod tests {
                 .as_bytes(),
         )
         .await;
+    }
 
+    #[async_std::test]
+    async fn test_subject_mdn() {
         // 5. Receive an mdn (read receipt) and make sure the mdn's subject is not used
         let t = TestContext::new_alice().await;
         dc_receive_imf(
             &t,
             b"Received: (Postfix, from userid 1000); Mon, 4 Dec 2006 14:51:39 +0100 (CET)\n\
             From: alice@example.com\n\
-            To: Charlie <charlie@example.com>\n\
+            To: bob@example.com\n\
-            Subject: Hello, Charlie\n\
+            Subject: Hello, Bob\n\
             Chat-Version: 1.0\n\
             Message-ID: <2893@example.com>\n\
             Date: Sun, 22 Mar 2020 22:37:56 +0000\n\
@@ -1489,7 +1520,7 @@ mod tests {
         .unwrap();
         let new_msg = incoming_msg_to_reply_msg(
             b"Received: (Postfix, from userid 1000); Mon, 4 Dec 2006 14:51:39 +0100 (CET)\n\
-                 From: charlie@example.com\n\
+                 From: bob@example.com\n\
                  To: alice@example.com\n\
                  Subject: message opened\n\
                  Date: Sun, 22 Mar 2020 23:37:57 +0000\n\
@@ -1508,14 +1539,78 @@ mod tests {
                  Content-Type: message/disposition-notification\n\
                  \n\
                  Reporting-UA: Delta Chat 1.28.0\n\
-                 Original-Recipient: rfc822;charlie@example.com\n\
+                 Original-Recipient: rfc822;bob@example.com\n\
-                 Final-Recipient: rfc822;charlie@example.com\n\
+                 Final-Recipient: rfc822;bob@example.com\n\
                  Original-Message-ID: <2893@example.com>\n\
                  Disposition: manual-action/MDN-sent-automatically; displayed\n\
                  \n", &t).await;
         let mf = MimeFactory::from_msg(&t, &new_msg, false).await.unwrap();
         // The subject string should not be "Re: message opened"
-        assert_eq!("Re: Hello, Charlie", mf.subject_str(&t).await);
+        assert_eq!("Re: Hello, Bob", mf.subject_str(&t).await.unwrap());
+    }
+
+    #[async_std::test]
+    async fn test_subject_in_group() {
+        // 6. Test that in a group, replies also take the quoted message's subject, while non-replies use the group title as subject
+        let t = TestContext::new_alice().await;
+        let group_id =
+            chat::create_group_chat(&t, chat::ProtectionStatus::Unprotected, "groupname")
+                .await
+                .unwrap();
+        let bob = Contact::create(&t, "", "bob@example.org").await.unwrap();
+        chat::add_contact_to_chat(&t, group_id, bob).await;
+
+        async fn send_msg_get_subject(
+            t: &TestContext,
+            group_id: ChatId,
+            quote: Option<&Message>,
+        ) -> String {
+            let mut new_msg = Message::new(Viewtype::Text);
+            new_msg.set_text(Some("Hi".to_string()));
+            if let Some(q) = quote {
+                new_msg.set_quote(t, q).await.unwrap();
+            }
+            let sent = t.send_msg(group_id, &mut new_msg).await;
+            t.parse_msg(&sent).await.get_subject().unwrap()
+        }
+
+        let subject = send_msg_get_subject(&t, group_id, None).await;
+        assert_eq!(subject, "groupname");
+
+        let subject = send_msg_get_subject(&t, group_id, None).await;
+        assert_eq!(subject, "Re: groupname");
+
+        dc_receive_imf(
+            &t,
+            format!(
+                "Received: (Postfix, from userid 1000); Mon, 4 Dec 2006 14:51:39 +0100 (CET)\n\
+                From: bob@example.com\n\
+                To: alice@example.com\n\
+                Subject: Different subject\n\
+                In-Reply-To: {}\n\
+                Message-ID: <2893@example.com>\n\
+                Date: Sun, 22 Mar 2020 22:37:56 +0000\n\
+                \n\
+                hello\n",
+                t.get_last_msg().await.rfc724_mid
+            )
+            .as_bytes(),
+            "INBOX",
+            5,
+            false,
+        )
+        .await
+        .unwrap();
+        let message_from_bob = t.get_last_msg().await;
+
+        let subject = send_msg_get_subject(&t, group_id, None).await;
+        assert_eq!(subject, "Re: groupname");
+
+        let subject = send_msg_get_subject(&t, group_id, Some(&message_from_bob)).await;
+        assert_eq!(subject, "Re: Different subject");
+
+        let subject = send_msg_get_subject(&t, group_id, None).await;
+        assert_eq!(subject, "Re: groupname");
     }
 
     async fn first_subject_str(t: TestContext) -> String {
@@ -1534,14 +1629,93 @@ mod tests {
 
         let mf = MimeFactory::from_msg(&t, &new_msg, false).await.unwrap();
 
-        mf.subject_str(&t).await
+        mf.subject_str(&t).await.unwrap()
     }
 
+    // In `imf_raw`, From has to be bob@example.com, To has to be alice@example.com
     async fn msg_to_subject_str(imf_raw: &[u8]) -> String {
+        let subject_str = msg_to_subject_str_inner(imf_raw, false, false, false).await;
+
+        // Check that combinations of true and false reproduce the same subject_str:
+        assert_eq!(
+            subject_str,
+            msg_to_subject_str_inner(imf_raw, true, false, false).await
+        );
+        assert_eq!(
+            subject_str,
+            msg_to_subject_str_inner(imf_raw, false, true, false).await
+        );
+        assert_eq!(
+            subject_str,
+            msg_to_subject_str_inner(imf_raw, false, true, true).await
+        );
+        assert_eq!(
+            subject_str,
+            msg_to_subject_str_inner(imf_raw, true, true, false).await
+        );
+
+        // These two combinations are different: If `message_arrives_inbetween` is true, but
+        // `reply` is false, the core is actually expected to use the subject of the message
+        // that arrived inbetween.
+        assert_eq!(
+            "Re: Some other, completely unrelated subject",
+            msg_to_subject_str_inner(imf_raw, false, false, true).await
+        );
+        assert_eq!(
+            "Re: Some other, completely unrelated subject",
+            msg_to_subject_str_inner(imf_raw, true, false, true).await
+        );
+
+        // We leave away the combination (true, true, true) here:
+        // It would mean that the original message is quoted without sending the quoting message
+        // out yet, then the original message is deleted, then another unrelated message arrives
+        // and then the message with the quote is sent out. Not very realistic.
+
+        subject_str
+    }
+
+    async fn msg_to_subject_str_inner(
+        imf_raw: &[u8],
+        delete_original_msg: bool,
+        reply: bool,
+        message_arrives_inbetween: bool,
+    ) -> String {
         let t = TestContext::new_alice().await;
-        let new_msg = incoming_msg_to_reply_msg(imf_raw, &t).await;
+        let mut new_msg = incoming_msg_to_reply_msg(imf_raw, &t).await;
+        let incoming_msg = get_chat_msg(&t, new_msg.chat_id, 0, 2).await;
+
+        if delete_original_msg {
+            incoming_msg.id.delete_from_db(&t).await.unwrap();
+        }
+
+        if message_arrives_inbetween {
+            dc_receive_imf(
+                &t,
+                b"Received: (Postfix, from userid 1000); Mon, 4 Dec 2006 14:51:39 +0100 (CET)\n\
+                    From: Bob <bob@example.com>\n\
+                    To: alice@example.com\n\
+                    Subject: Some other, completely unrelated subject\n\
+                    Message-ID: <3cl4@example.com>\n\
+                    Date: Sun, 22 Mar 2020 22:37:56 +0000\n\
+                    \n\
+                    Some other, completely unrelated content\n",
+                "INBOX",
+                2,
+                false,
+            )
+            .await
+            .unwrap();
+
+            let arrived_msg = t.get_last_msg().await;
+            assert_eq!(arrived_msg.chat_id, incoming_msg.chat_id);
+        }
+
+        if reply {
+            new_msg.set_quote(&t, &incoming_msg).await.unwrap();
+        }
+
         let mf = MimeFactory::from_msg(&t, &new_msg, false).await.unwrap();
-        mf.subject_str(&t).await
+        mf.subject_str(&t).await.unwrap()
     }
 
     // Creates a `Message` that replies "Hi" to the incoming email in `imf_raw`.

src/param.rs

@@ -126,7 +126,9 @@ pub enum Param {
     /// For Chats
     Selftalk = b'K',
 
-    /// For Chats: So that on sending a new message we can sent the subject to "Re: <last subject>"
+    /// For Chats: On sending a new message we set the subject to "Re: <last subject>".
+    /// Usually we just use the subject of the parent message, but if the parent message
+    /// is deleted, we use the LastSubject of the chat.
     LastSubject = b't',
 
     /// For Chats

src/sql.rs

@@ -1504,6 +1504,15 @@ CREATE INDEX devmsglabels_index1 ON devmsglabels (label);
             .await?;
             sql.set_raw_config_int(context, "dbversion", 75).await?;
         }
+        if dbversion < 76 {
+            info!(context, "[migration] v76");
+            sql.execute(
+                "ALTER TABLE msgs ADD COLUMN subject TEXT DEFAULT '';",
+                paramsv![],
+            )
+            .await?;
+            sql.set_raw_config_int(context, "dbversion", 76).await?;
+        }
 
         // (2) updates that require high-level objects
         // (the structure is complete now and all objects are usable)

src/test_utils.rs

@@ -9,10 +9,10 @@ use std::{collections::BTreeMap, panic};
 use std::{fmt, thread};
 
 use ansi_term::Color;
-use async_std::future::Future;
 use async_std::path::PathBuf;
 use async_std::sync::{Arc, RwLock};
 use async_std::{channel, pin::Pin};
+use async_std::{future::Future, task};
 use chat::ChatItem;
 use once_cell::sync::Lazy;
 use tempfile::{tempdir, TempDir};
@@ -20,6 +20,7 @@ use tempfile::{tempdir, TempDir};
 use crate::chat::{self, Chat, ChatId};
 use crate::chatlist::Chatlist;
 use crate::config::Config;
+use crate::constants::Chattype;
 use crate::constants::{Viewtype, DC_CONTACT_ID_SELF, DC_MSG_ID_DAYMARKER, DC_MSG_ID_MARKER1};
 use crate::contact::{Contact, Origin};
 use crate::context::Context;
@@ -102,9 +103,12 @@ impl TestContext {
         let (poison_sender, poison_receiver) = channel::bounded(1);
         async_std::task::spawn(async move {
             // Make sure that the test fails if there is a panic on this thread here:
+            let current_id = task::current().id();
             let orig_hook = panic::take_hook();
             panic::set_hook(Box::new(move |panic_info| {
-                poison_sender.try_send(panic_info.to_string()).ok();
+                if task::current().id() == current_id {
+                    poison_sender.try_send(panic_info.to_string()).ok();
+                }
                 orig_hook(panic_info);
             }));
 
@@ -310,7 +314,11 @@ impl TestContext {
     /// Gets the most recent message over all chats.
     pub async fn get_last_msg(&self) -> Message {
         let chats = Chatlist::try_load(&self.ctx, 0, None, None).await.unwrap();
-        let msg_id = chats.get_msg_id(chats.len() - 1).unwrap();
+        // 0 is correct in the next line (as opposed to `chats.len() - 1`, which would be the last element):
+        // The chatlist describes what you see when you open DC, a list of chats and in each of them
+        // the first words of the last message. To get the last message overall, we look at the chat at the top of the
+        // list, which has the index 0.
+        let msg_id = chats.get_msg_id(0).unwrap();
         Message::load_from_db(&self.ctx, msg_id).await.unwrap()
     }
 
@@ -364,8 +372,17 @@ impl TestContext {
     pub async fn send_text(&self, chat_id: ChatId, txt: &str) -> SentMessage {
         let mut msg = Message::new(Viewtype::Text);
         msg.set_text(Some(txt.to_string()));
-        chat::prepare_msg(self, chat_id, &mut msg).await.unwrap();
+        self.send_msg(chat_id, &mut msg).await
-        chat::send_msg(self, chat_id, &mut msg).await.unwrap();
+    }
+
+    /// Sends out the message to the specified chat.
+    ///
+    /// This is not hooked up to any SMTP-IMAP pipeline, so the other account must call
+    /// [`TestContext::recv_msg`] with the returned [`SentMessage`] if it wants to receive
+    /// the message.
+    pub async fn send_msg(&self, chat_id: ChatId, msg: &mut Message) -> SentMessage {
+        chat::prepare_msg(self, chat_id, msg).await.unwrap();
+        chat::send_msg(self, chat_id, msg).await.unwrap();
         self.pop_sent_msg().await
     }
 
@@ -375,8 +392,9 @@ impl TestContext {
     // This code is mainly the same as `log_msglist` in `cmdline.rs`, so one day, we could
     // merge them to a public function in the `deltachat` crate.
     #[allow(dead_code)]
-    pub async fn print_chat(&self, chat: &Chat) {
+    #[allow(clippy::clippy::indexing_slicing)]
-        let msglist = chat::get_chat_msgs(self, chat.get_id(), 0x1, None).await;
+    pub async fn print_chat(&self, chat_id: ChatId) {
+        let msglist = chat::get_chat_msgs(self, chat_id, 0x1, None).await;
         let msglist: Vec<MsgId> = msglist
             .into_iter()
             .map(|x| match x {
@@ -386,6 +404,44 @@ impl TestContext {
             })
             .collect();
 
+        let sel_chat = Chat::load_from_db(self, chat_id).await.unwrap();
+        let members = chat::get_chat_contacts(self, sel_chat.id).await;
+        let subtitle = if sel_chat.is_device_talk() {
+            "device-talk".to_string()
+        } else if sel_chat.get_type() == Chattype::Single && !members.is_empty() {
+            let contact = Contact::get_by_id(self, members[0]).await.unwrap();
+            contact.get_addr().to_string()
+        } else if sel_chat.get_type() == Chattype::Mailinglist && !members.is_empty() {
+            "mailinglist".to_string()
+        } else {
+            format!("{} member(s)", members.len())
+        };
+        println!(
+            "{}#{}: {} [{}]{}{}{} {}",
+            sel_chat.typ,
+            sel_chat.get_id(),
+            sel_chat.get_name(),
+            subtitle,
+            if sel_chat.is_muted() { "🔇" } else { "" },
+            if sel_chat.is_sending_locations() {
+                "📍"
+            } else {
+                ""
+            },
+            match sel_chat.get_profile_image(self).await {
+                Some(icon) => match icon.to_str() {
+                    Some(icon) => format!(" Icon: {}", icon),
+                    _ => " Icon: Err".to_string(),
+                },
+                _ => "".to_string(),
+            },
+            if sel_chat.is_protected() {
+                "🛡️"
+            } else {
+                ""
+            },
+        );
+
         let mut lines_out = 0;
         for msg_id in msglist {
             if msg_id == MsgId::new(DC_MSG_ID_DAYMARKER) {