diff --git a/src/lib.rs b/src/lib.rs
index c734d85..fb9c764 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,7 +10,7 @@ use isolang::Language;
 use message::{Message, MessageAction, MessageID};
 use queue::{
     data_director::{RegMsg, Register},
-    router::Queue,
+    router::{ClockType, Queue, SystemClock, TestClock},
     SenderID,
 };
 use std::{
@@ -224,7 +224,14 @@ pub struct MoreThanText {
 
 impl MoreThanText {
     pub fn new() -> Self {
-        let queue = Queue::new();
+        Self::with_clock(SystemClock::new())
+    }
+
+    fn with_clock<C>(clock: C) -> Self
+    where
+        C: Into<ClockType>,
+    {
+        let queue = Queue::with_clock(clock);
         CreateDoc::start(queue.clone()); // needs to be first.
         Clock::start(queue.clone());
         Session::start(queue.clone());
@@ -253,6 +260,7 @@ impl MoreThanText {
 }
 
 pub struct TestMoreThanText {
+    clock: TestClock,
     mtt: MoreThanText,
     queue: Queue,
     channel: Option<Receiver<Message>>,
@@ -260,9 +268,11 @@ pub struct TestMoreThanText {
 
 impl TestMoreThanText {
     pub fn new() -> Self {
-        let mtt = MoreThanText::new();
+        let clock = TestClock::new();
+        let mtt = MoreThanText::with_clock(clock.clone());
         let queue = mtt.queue.clone();
         Self {
+            clock: clock,
             mtt: mtt,
             queue: queue,
             channel: None,
@@ -312,4 +322,8 @@ impl TestMoreThanText {
             panic!("received {:?} instead of {:?} trigger", msg, action);
         }
     }
+
+    pub fn advance_time(&self, duration: Duration) {
+        self.clock.advance(duration);
+    }
 }
diff --git a/src/queue.rs b/src/queue.rs
index 12a91bf..7cce91a 100644
--- a/src/queue.rs
+++ b/src/queue.rs
@@ -1,4 +1,4 @@
 pub mod data_director;
 pub mod router;
 
-pub use router::SenderID;
+pub use router::{ClockType, SenderID, SystemClock, TestClock};
diff --git a/src/queue/router.rs b/src/queue/router.rs
index 5aa928e..89ca50f 100644
--- a/src/queue/router.rs
+++ b/src/queue/router.rs
@@ -2,12 +2,14 @@ use crate::{
     message::Message,
     queue::data_director::{DocRegistry, RegMsg, Register},
 };
+use chrono::{DateTime, Utc};
 use std::{
     collections::HashMap,
     sync::{
         mpsc::{channel, Sender},
         Arc, RwLock,
     },
+    time::Duration,
 };
 use uuid::Uuid;
 
@@ -89,16 +91,115 @@ impl Router {
     }
 }
 
+trait Now {
+    fn now(&self) -> DateTime<Utc> {
+        Utc::now()
+    }
+}
+
+pub struct SystemClock;
+
+impl SystemClock {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
+
+impl Now for SystemClock {}
+
+#[derive(Clone)]
+pub struct TestClock {
+    time: Arc<RwLock<DateTime<Utc>>>,
+}
+
+impl TestClock {
+    pub fn new() -> Self {
+        Self {
+            time: Arc::new(RwLock::new(Utc::now())),
+        }
+    }
+
+    pub fn advance(&self, duration: Duration) {
+        let mut current = self.time.write().unwrap();
+        *current += duration;
+    }
+}
+
+impl Now for TestClock {
+    fn now(&self) -> DateTime<Utc> {
+        let current = self.time.read().unwrap();
+        current.clone()
+    }
+}
+
+#[cfg(test)]
+mod test_clocks {
+    use super::*;
+
+    #[test]
+    fn is_now_constant() {
+        let clock = TestClock::new();
+        let read1 = clock.now();
+        let read2 = clock.now();
+        assert_eq!(read1, read2);
+    }
+
+    #[test]
+    fn can_time_pass() {
+        let clock = TestClock::new();
+        let current = clock.now();
+        let duration = Duration::from_secs(35);
+        let expected = current + duration;
+        clock.advance(duration);
+        assert_eq!(clock.now(), expected);
+    }
+}
+
+pub enum ClockType {
+    Clock(SystemClock),
+    TestClock(TestClock),
+}
+
+impl Now for ClockType {
+    fn now(&self) -> DateTime<Utc> {
+        match self {
+            Self::Clock(data) => data.now(),
+            Self::TestClock(data) => data.now(),
+        }
+    }
+}
+
+impl From<SystemClock> for ClockType {
+    fn from(value: SystemClock) -> Self {
+        Self::Clock(value)
+    }
+}
+
+impl From<TestClock> for ClockType {
+    fn from(value: TestClock) -> Self {
+        Self::TestClock(value)
+    }
+}
+
 #[derive(Clone)]
 pub struct Queue {
     router: Arc<RwLock<Router>>,
+    clock: Arc<RwLock<ClockType>>,
 }
 
 impl Queue {
     pub fn new() -> Self {
+        Self::with_clock(SystemClock::new())
+    }
+
+    pub fn with_clock<C>(clock: C) -> Self
+    where
+        C: Into<ClockType>,
+    {
         let (tx, rx) = channel();
         let output = Self {
             router: Arc::new(RwLock::new(Router::new(tx))),
+            clock: Arc::new(RwLock::new(clock.into())),
         };
         DocRegistry::start(output.clone(), rx);
         output
@@ -123,6 +224,11 @@ impl Queue {
         let router = self.router.read().unwrap();
         router.send(msg.clone());
     }
+
+    pub fn now(&self) -> DateTime<Utc> {
+        let clock = self.clock.read().unwrap();
+        clock.now()
+    }
 }
 
 #[cfg(test)]
@@ -357,4 +463,16 @@ mod queues {
             _ => unreachable!("got {:?} should have been register", action),
         }
     }
+
+    #[test]
+    fn does_queue_return_time() {
+        let clock = TestClock::new();
+        let queue = Queue::with_clock(clock.clone());
+        let mut expected = clock.now();
+        assert_eq!(queue.now(), expected);
+        let forward = Duration::from_secs(22);
+        clock.advance(forward);
+        expected += forward;
+        assert_eq!(queue.now(), expected);
+    }
 }