diff --git a/src/crypto/device.rs b/src/crypto/device.rs
index c5d50a32..cfde349c 100644
--- a/src/crypto/device.rs
+++ b/src/crypto/device.rs
@@ -18,9 +18,9 @@ use std::sync::Arc;
 
 use atomic::Atomic;
 
-use ruma_client_api::r0::keys::{DeviceKeys, KeyAlgorithm};
-use ruma_events::Algorithm;
-use ruma_identifiers::{DeviceId, UserId};
+use crate::api::r0::keys::{DeviceKeys, KeyAlgorithm};
+use crate::events::Algorithm;
+use crate::identifiers::{DeviceId, UserId};
 
 #[derive(Debug, Clone)]
 pub struct Device {
@@ -82,3 +82,61 @@ impl From<&DeviceKeys> for Device {
         }
     }
 }
+
+impl PartialEq for Device {
+    fn eq(&self, other: &Self) -> bool {
+        self.user_id() == other.user_id() && self.device_id() == other.device_id()
+    }
+}
+
+#[cfg(test)]
+pub(crate) mod test {
+    use serde_json::json;
+    use std::convert::{From, TryFrom};
+
+    use crate::api::r0::keys::DeviceKeys;
+    use crate::crypto::device::Device;
+    use crate::identifiers::UserId;
+
+    pub(crate) fn get_device() -> Device {
+        let user_id = UserId::try_from("@alice:example.org").unwrap();
+        let device_id = "DEVICEID";
+
+        let device_keys = json!({
+          "algorithms": vec![
+              "m.olm.v1.curve25519-aes-sha2",
+              "m.megolm.v1.aes-sha2"
+          ],
+          "device_id": device_id,
+          "user_id": user_id.to_string(),
+          "keys": {
+              "curve25519:DEVICEID": "wjLpTLRqbqBzLs63aYaEv2Boi6cFEbbM/sSRQ2oAKk4",
+              "ed25519:DEVICEID": "nE6W2fCblxDcOFmeEtCHNl8/l8bXcu7GKyAswA4r3mM"
+          },
+          "signatures": {
+              user_id.to_string(): {
+                  "ed25519:DEVICEID": "m53Wkbh2HXkc3vFApZvCrfXcX3AI51GsDHustMhKwlv3TuOJMj4wistcOTM8q2+e/Ro7rWFUb9ZfnNbwptSUBA"
+              }
+          },
+          "unsigned": {
+              "device_display_name": "Alice's mobile phone"
+          }
+        });
+
+        let device_keys: DeviceKeys = serde_json::from_value(device_keys).unwrap();
+
+        Device::from(&device_keys)
+    }
+
+    #[test]
+    fn create_a_device() {
+        let user_id = UserId::try_from("@alice:example.org").unwrap();
+        let device_id = "DEVICEID";
+
+        let device = get_device();
+
+        assert_eq!(&user_id, device.user_id());
+        assert_eq!(device_id, device.device_id());
+        assert_eq!(device.algorithms.len(), 2);
+    }
+}
diff --git a/src/crypto/memory_stores.rs b/src/crypto/memory_stores.rs
index 2d9f5e11..b0e39bb6 100644
--- a/src/crypto/memory_stores.rs
+++ b/src/crypto/memory_stores.rs
@@ -114,36 +114,45 @@ impl GroupSessionStore {
     }
 }
 
+/// In-memory store holding the devices of users.
 #[derive(Clone, Debug)]
 pub struct DeviceStore {
     entries: Arc<DashMap<UserId, DashMap<String, Device>>>,
 }
 
+/// A read only view over all devices belonging to a user.
 pub struct UserDevices {
     entries: ReadOnlyView<DeviceId, Device>,
 }
 
 impl UserDevices {
+    /// Get the specific device with the given device id.
     pub fn get(&self, device_id: &str) -> Option<Device> {
         self.entries.get(device_id).cloned()
     }
 
+    /// Iterator over all the device ids of the user devices.
     pub fn keys(&self) -> impl Iterator<Item = &DeviceId> {
         self.entries.keys()
     }
 
+    /// Iterator over all the devices of the user devices.
     pub fn devices(&self) -> impl Iterator<Item = &Device> {
         self.entries.values()
     }
 }
 
 impl DeviceStore {
+    /// Create a new empty device store.
     pub fn new() -> Self {
         DeviceStore {
             entries: Arc::new(DashMap::new()),
         }
     }
 
+    /// Add a device to the store.
+    ///
+    /// Returns true if the device was already in the store, false otherwise.
     pub fn add(&self, device: Device) -> bool {
         let user_id = device.user_id();
 
@@ -157,12 +166,14 @@ impl DeviceStore {
             .is_some()
     }
 
+    /// Get the device with the given device_id and belonging to the given user.
     pub fn get(&self, user_id: &UserId, device_id: &str) -> Option<Device> {
         self.entries
             .get(user_id)
             .and_then(|m| m.get(device_id).map(|d| d.value().clone()))
     }
 
+    /// Get a read-only view over all devices of the given user.
     pub fn user_devices(&self, user_id: &UserId) -> UserDevices {
         if !self.entries.contains_key(user_id) {
             self.entries.insert(user_id.clone(), DashMap::new());
@@ -179,6 +190,7 @@ mod test {
     use std::convert::TryFrom;
 
     use crate::api::r0::keys::SignedKey;
+    use crate::crypto::device::test::get_device;
     use crate::crypto::memory_stores::{DeviceStore, GroupSessionStore, SessionStore};
     use crate::crypto::olm::{Account, InboundGroupSession, OutboundGroupSession, Session};
     use crate::identifiers::RoomId;
@@ -226,6 +238,21 @@ mod test {
         assert_eq!(&session, loaded_session);
     }
 
+    #[tokio::test]
+    async fn test_session_store_bulk_storing() {
+        let (account, session) = get_account_and_session().await;
+
+        let mut store = SessionStore::new();
+        store.set_for_sender(&session.sender_key, vec![session.clone()]);
+
+        let sessions = store.get(&session.sender_key).unwrap();
+        let sessions = sessions.lock().await;
+
+        let loaded_session = &sessions[0];
+
+        assert_eq!(&session, loaded_session);
+    }
+
     #[tokio::test]
     async fn test_group_session_store() {
         let alice = Account::new();
@@ -254,4 +281,26 @@ mod test {
             .unwrap();
         assert_eq!(inbound, loaded_session);
     }
+
+    #[tokio::test]
+    async fn test_device_store() {
+        let device = get_device();
+        let store = DeviceStore::new();
+
+        assert!(!store.add(device.clone()));
+        assert!(store.add(device.clone()));
+
+        let loaded_device = store.get(device.user_id(), device.device_id()).unwrap();
+
+        assert_eq!(device, loaded_device);
+
+        let user_devices = store.user_devices(device.user_id());
+
+        assert_eq!(user_devices.keys().nth(0).unwrap(), device.device_id());
+        assert_eq!(user_devices.devices().nth(0).unwrap(), &device);
+
+        let loaded_device = user_devices.get(device.device_id()).unwrap();
+
+        assert_eq!(device, loaded_device);
+    }
 }