diff --git a/music-player/server/src/bin/server.rs b/music-player/server/src/bin/server.rs
index 519ac16..e6c8208 100644
--- a/music-player/server/src/bin/server.rs
+++ b/music-player/server/src/bin/server.rs
@@ -50,6 +50,7 @@ fn tracks() -> Vec<Track> {
 
 #[tokio::main]
 pub async fn main() {
+    /*
     match Core::new(Arc::new(MemoryIndex::new())) {
         Flow::Ok(core) => {
             let mut buf = String::new();
@@ -59,6 +60,7 @@ pub async fn main() {
         Flow::Err(err) => println!("non-fatal error: {:?}", err),
         Flow::Fatal(err) => println!("fatal error: {:?}", err),
     }
+    */
 
     /*
     let connection = Connection::new_session().expect("to connect to dbus");
diff --git a/music-player/server/src/core.rs b/music-player/server/src/core.rs
index 60f614c..69215c6 100644
--- a/music-player/server/src/core.rs
+++ b/music-player/server/src/core.rs
@@ -1,11 +1,8 @@
 use crate::{
-    audio::TrackInfo,
-    database::{Database, MemoryIndex, MusicIndex},
-    Error, FatalError,
+    audio::TrackInfo, database::MusicIndex, music_scanner::MusicScanner, Error, FatalError,
 };
-use flow::{error, fatal, ok, return_error, return_fatal, Flow};
+use flow::{ok, Flow};
 use std::{
-    path::{Path, PathBuf},
     sync::{
         mpsc::{channel, Receiver, RecvTimeoutError, Sender},
         Arc,
@@ -15,12 +12,17 @@ use std::{
     time::{Duration, Instant},
 };
 
+fn scan_frequency() -> Duration {
+    Duration::from_secs(60)
+}
+
 pub enum ControlMsg {
     Exit,
 }
 
 pub enum TrackMsg {
-    DbUpdate,
+    UpdateInProgress,
+    UpdateComplete,
 }
 
 pub enum PlaybackMsg {
@@ -32,36 +34,58 @@ pub enum PlaybackMsg {
 
 pub struct Core {
     db: Arc<dyn MusicIndex>,
-    track_handle: JoinHandle<()>,
-    track_rx: Receiver<TrackMsg>,
-    playback_handle: JoinHandle<()>,
-    playback_rx: Receiver<PlaybackMsg>,
+    _track_handle: JoinHandle<()>,
+    _track_rx: Receiver<TrackMsg>,
+    _playback_handle: JoinHandle<()>,
+    _playback_rx: Receiver<PlaybackMsg>,
     control_tx: Sender<ControlMsg>,
 }
 
 impl Core {
-    pub fn new(db: Arc<dyn MusicIndex>) -> Flow<Core, FatalError, Error> {
+    pub fn new(
+        db: Arc<dyn MusicIndex>,
+        scanner: impl MusicScanner + 'static,
+    ) -> Flow<Core, FatalError, Error> {
         let (control_tx, control_rx) = channel::<ControlMsg>();
 
-        let (track_handle, track_rx) = {
+        let (_track_handle, _track_rx) = {
             let (track_tx, track_rx) = channel();
             let db = db.clone();
-            let track_handle = thread::spawn(move || {});
+            let track_handle = thread::spawn(move || {
+                println!("tracker thread started");
+                let mut next_scan = Instant::now();
+                loop {
+                    if Instant::now() >= next_scan {
+                        let _ = track_tx.send(TrackMsg::UpdateInProgress);
+                        for track in scanner.scan() {
+                            println!("scanning {:?}", track);
+                            db.add_track(track);
+                        }
+                        let _ = track_tx.send(TrackMsg::UpdateComplete);
+                        next_scan = Instant::now() + scan_frequency();
+                    }
+                    match control_rx.recv_timeout(Duration::from_millis(1000)) {
+                        Ok(ControlMsg::Exit) => return,
+                        Err(RecvTimeoutError::Timeout) => (),
+                        Err(RecvTimeoutError::Disconnected) => return,
+                    }
+                }
+            });
             (track_handle, track_rx)
         };
 
-        let (playback_handle, playback_rx) = {
-            let (playback_tx, playback_rx) = channel();
+        let (_playback_handle, _playback_rx) = {
+            let (_playback_tx, playback_rx) = channel();
             let playback_handle = thread::spawn(move || {});
             (playback_handle, playback_rx)
         };
 
         ok(Core {
             db,
-            track_handle,
-            track_rx,
-            playback_handle,
-            playback_rx,
+            _track_handle,
+            _track_rx,
+            _playback_handle,
+            _playback_rx,
             control_tx,
         })
     }
@@ -82,7 +106,7 @@ impl Core {
 #[cfg(test)]
 mod test {
     use super::*;
-    use crate::audio::{TrackId, TrackInfo};
+    use crate::{audio::TrackId, database::MemoryIndex, music_scanner::factories::MockScanner};
     use std::collections::HashSet;
 
     fn with_example_index<F>(f: F)
@@ -90,43 +114,12 @@ mod test {
         F: Fn(Core),
     {
         let index = MemoryIndex::new();
-        index.add_track(TrackInfo {
-            id: TrackId::from("/home/savanni/Track 1.mp3".to_owned()),
-            track_number: None,
-            name: None,
-            album: None,
-            artist: None,
-        });
-        index.add_track(TrackInfo {
-            id: TrackId::from("/home/savanni/Track 2.mp3".to_owned()),
-            track_number: None,
-            name: None,
-            album: None,
-            artist: None,
-        });
-        index.add_track(TrackInfo {
-            id: TrackId::from("/home/savanni/Track 3.mp3".to_owned()),
-            track_number: None,
-            name: None,
-            album: None,
-            artist: None,
-        });
-        index.add_track(TrackInfo {
-            id: TrackId::from("/home/savanni/Track 4.mp3".to_owned()),
-            track_number: None,
-            name: None,
-            album: None,
-            artist: None,
-        });
-        index.add_track(TrackInfo {
-            id: TrackId::from("/home/savanni/Track 5.mp3".to_owned()),
-            track_number: None,
-            name: None,
-            album: None,
-            artist: None,
-        });
-        match Core::new(Arc::new(index)) {
-            Flow::Ok(core) => f(core),
+        let scanner = MockScanner::new();
+        match Core::new(Arc::new(index), scanner) {
+            Flow::Ok(core) => {
+                thread::sleep(Duration::from_millis(10));
+                f(core)
+            }
             Flow::Err(error) => panic!("{:?}", error),
             Flow::Fatal(error) => panic!("{:?}", error),
         }
diff --git a/music-player/server/src/music_scanner.rs b/music-player/server/src/music_scanner.rs
index d22480e..57d071e 100644
--- a/music-player/server/src/music_scanner.rs
+++ b/music-player/server/src/music_scanner.rs
@@ -1,4 +1,5 @@
 use crate::{
+    audio::TrackInfo,
     core::{ControlMsg, TrackMsg},
     database::MusicIndex,
     FatalError,
@@ -14,10 +15,6 @@ use std::{
 };
 use thiserror::Error;
 
-fn scan_frequency() -> Duration {
-    Duration::from_secs(60)
-}
-
 #[derive(Debug, Error)]
 pub enum ScannerError {
     #[error("Cannot scan {0}")]
@@ -32,50 +29,26 @@ impl From<std::io::Error> for ScannerError {
     }
 }
 
-pub trait MusicScanner {
-    fn scan(&self);
+pub trait MusicScanner: Send {
+    fn scan<'a>(&'a self) -> Box<dyn Iterator<Item = TrackInfo> + 'a>;
 }
 
+/*
 pub struct FileScanner {
     db: Arc<dyn MusicIndex>,
-    control_rx: Receiver<ControlMsg>,
     tracker_tx: Sender<TrackMsg>,
-    next_scan: Instant,
     music_directories: Vec<PathBuf>,
 }
 
 impl FileScanner {
-    fn new(
-        db: Arc<dyn MusicIndex>,
-        roots: Vec<PathBuf>,
-        control_rx: Receiver<ControlMsg>,
-        tracker_tx: Sender<TrackMsg>,
-    ) -> Self {
+    fn new(db: Arc<dyn MusicIndex>, roots: Vec<PathBuf>, tracker_tx: Sender<TrackMsg>) -> Self {
         Self {
             db,
-            control_rx,
             tracker_tx,
-            next_scan: Instant::now(),
             music_directories: roots,
         }
     }
 
-    fn scan(&mut self) {
-        loop {
-            match self.control_rx.recv_timeout(Duration::from_millis(100)) {
-                Ok(ControlMsg::Exit) => return,
-                Err(RecvTimeoutError::Timeout) => (),
-                Err(RecvTimeoutError::Disconnected) => return,
-            }
-            if Instant::now() >= self.next_scan {
-                for root in self.music_directories.iter() {
-                    self.scan_dir(vec![root.clone()]);
-                }
-                self.next_scan = Instant::now() + scan_frequency();
-            }
-        }
-    }
-
     fn scan_dir(&self, mut paths: Vec<PathBuf>) -> Flow<(), FatalError, ScannerError> {
         while let Some(dir) = paths.pop() {
             println!("scanning {:?}", dir);
@@ -112,3 +85,85 @@ impl FileScanner {
         ok(())
     }
 }
+
+impl MusicScanner for FileScanner {
+    fn scan<'a>(&'a self) -> Box<&'a dyn Iterator<Item = TrackInfo>> {
+        unimplemented!()
+        /*
+        loop {
+            match self.control_rx.recv_timeout(Duration::from_millis(100)) {
+                Ok(ControlMsg::Exit) => return,
+                Err(RecvTimeoutError::Timeout) => (),
+                Err(RecvTimeoutError::Disconnected) => return,
+            }
+            if Instant::now() >= self.next_scan {
+                for root in self.music_directories.iter() {
+                    self.scan_dir(vec![root.clone()]);
+                }
+                self.next_scan = Instant::now() + scan_frequency();
+            }
+        }
+        */
+    }
+}
+*/
+
+#[cfg(test)]
+pub mod factories {
+    use super::*;
+    use crate::audio::TrackId;
+
+    pub struct MockScanner {
+        data: Vec<TrackInfo>,
+    }
+
+    impl MockScanner {
+        pub fn new() -> Self {
+            Self {
+                data: vec![
+                    TrackInfo {
+                        id: TrackId::from("/home/savanni/Track 1.mp3".to_owned()),
+                        track_number: Some(1),
+                        name: Some("Track 1".to_owned()),
+                        album: Some("Savanni's Demo".to_owned()),
+                        artist: Some("Savanni".to_owned()),
+                    },
+                    TrackInfo {
+                        id: TrackId::from("/home/savanni/Track 2.mp3".to_owned()),
+                        track_number: Some(2),
+                        name: Some("Track 2".to_owned()),
+                        album: Some("Savanni's Demo".to_owned()),
+                        artist: Some("Savanni".to_owned()),
+                    },
+                    TrackInfo {
+                        id: TrackId::from("/home/savanni/Track 3.mp3".to_owned()),
+                        track_number: Some(3),
+                        name: Some("Track 3".to_owned()),
+                        album: Some("Savanni's Demo".to_owned()),
+                        artist: Some("Savanni".to_owned()),
+                    },
+                    TrackInfo {
+                        id: TrackId::from("/home/savanni/Track 4.mp3".to_owned()),
+                        track_number: Some(4),
+                        name: Some("Track 4".to_owned()),
+                        album: Some("Savanni's Demo".to_owned()),
+                        artist: Some("Savanni".to_owned()),
+                    },
+                    TrackInfo {
+                        id: TrackId::from("/home/savanni/Track 5.mp3".to_owned()),
+                        track_number: Some(5),
+                        name: Some("Track 5".to_owned()),
+                        album: Some("Savanni's Demo".to_owned()),
+                        artist: Some("Savanni".to_owned()),
+                    },
+                ],
+            }
+        }
+    }
+
+    impl MusicScanner for MockScanner {
+        fn scan<'a>(&'a self) -> Box<dyn Iterator<Item = TrackInfo> + 'a> {
+            Box::new(self.data.iter().map(|t| t.clone()))
+        }
+    }
+}