diff --git a/actix-utils/Cargo.toml b/actix-utils/Cargo.toml
index 6beb5816..ceef0afe 100644
--- a/actix-utils/Cargo.toml
+++ b/actix-utils/Cargo.toml
@@ -24,4 +24,7 @@ bytes = "0.4"
 futures = "0.1"
 tokio-timer = "0.2.8"
 tokio-current-thread = "0.1"
-log = "0.4"
\ No newline at end of file
+log = "0.4"
+
+[dev-dependencies]
+actix-rt = "0.1"
\ No newline at end of file
diff --git a/actix-utils/src/time.rs b/actix-utils/src/time.rs
index 2a83a5aa..d2bfe86a 100644
--- a/actix-utils/src/time.rs
+++ b/actix-utils/src/time.rs
@@ -153,3 +153,96 @@ impl SystemTimeService {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use futures::future;
+    use std::time::{Duration, SystemTime};
+
+    /// State Under Test: Two calls of `SystemTimeService::now()` return the same value if they are done within resolution interval of `SystemTimeService`.
+    ///
+    /// Expected Behavior: Two back-to-back calls of `SystemTimeService::now()` return the same value.
+    #[test]
+    fn system_time_service_time_does_not_immediately_change() {
+        let resolution = Duration::from_millis(50);
+
+        let _ = actix_rt::System::new("test").block_on(future::lazy(|| {
+            let time_service = SystemTimeService::with(resolution);
+
+            assert_eq!(time_service.now(), time_service.now());
+
+            Ok::<(), ()>(())
+        }));
+    }
+
+    /// State Under Test: Two calls of `LowResTimeService::now()` return the same value if they are done within resolution interval of `SystemTimeService`.
+    ///
+    /// Expected Behavior: Two back-to-back calls of `LowResTimeService::now()` return the same value.
+    #[test]
+    fn lowres_time_service_time_does_not_immediately_change() {
+        let resolution = Duration::from_millis(50);
+
+        let _ = actix_rt::System::new("test").block_on(future::lazy(|| {
+            let time_service = LowResTimeService::with(resolution);
+
+            assert_eq!(time_service.now(), time_service.now());
+
+            Ok::<(), ()>(())
+        }));
+    }
+
+    /// State Under Test: `SystemTimeService::now()` updates returned value every resolution period.
+    ///
+    /// Expected Behavior: Two calls of `LowResTimeService::now()` made in subsequent resolution interval return different values
+    /// and second value is greater than the first one at least by a resolution interval.
+    #[test]
+    fn system_time_service_time_updates_after_resolution_interval() {
+        let resolution = Duration::from_millis(100);
+        let wait_time = Duration::from_millis(150);
+
+        let _ = actix_rt::System::new("test").block_on(future::lazy(|| {
+            let time_service = SystemTimeService::with(resolution);
+
+            let first_time = time_service
+                .now()
+                .duration_since(SystemTime::UNIX_EPOCH)
+                .unwrap();
+
+            sleep(wait_time).then(move |_| {
+                let second_time = time_service
+                    .now()
+                    .duration_since(SystemTime::UNIX_EPOCH)
+                    .unwrap();
+
+                assert!(second_time - first_time >= wait_time);
+
+                Ok::<(), ()>(())
+            })
+        }));
+    }
+
+    /// State Under Test: `LowResTimeService::now()` updates returned value every resolution period.
+    ///
+    /// Expected Behavior: Two calls of `LowResTimeService::now()` made in subsequent resolution interval return different values
+    /// and second value is greater than the first one at least by a resolution interval.
+    #[test]
+    fn lowres_time_service_time_updates_after_resolution_interval() {
+        let resolution = Duration::from_millis(100);
+        let wait_time = Duration::from_millis(150);
+
+        let _ = actix_rt::System::new("test").block_on(future::lazy(|| {
+            let time_service = LowResTimeService::with(resolution);
+
+            let first_time = time_service.now();
+
+            sleep(wait_time).then(move |_| {
+                let second_time = time_service.now();
+
+                assert!(second_time - first_time >= wait_time);
+
+                Ok::<(), ()>(())
+            })
+        }));
+    }
+}