Added some tests.
diff --git a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DeviceStore.java b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DeviceStore.java
index f907e35..c874600 100644
--- a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DeviceStore.java
+++ b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/DeviceStore.java
@@ -2,6 +2,8 @@
 
 import org.onlab.onos.net.Device;
 import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.Port;
+import org.onlab.onos.net.PortNumber;
 import org.onlab.onos.net.device.DeviceDescription;
 import org.onlab.onos.net.device.DeviceEvent;
 import org.onlab.onos.net.device.PortDescription;
@@ -66,4 +68,35 @@
                                         PortDescription portDescription) {
         return null;
     }
+
+    /**
+     * Returns the device with the specified identifier.
+     *
+     * @param deviceId device identifier
+     * @return device
+     */
+    public Device getDevice(DeviceId deviceId) {
+        return null;
+    }
+
+    /**
+     * Returns the list of ports that belong to the specified device.
+     *
+     * @param deviceId device identifier
+     * @return list of device ports
+     */
+    public List<Port> getPorts(DeviceId deviceId) {
+        return null;
+    }
+
+    /**
+     * Returns the specified device port.
+     *
+     * @param deviceId   device identifier
+     * @param portNumber port number
+     * @return device port
+     */
+    public Port getPort(DeviceId deviceId, PortNumber portNumber) {
+        return null;
+    }
 }
diff --git a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
index 4344fd0..b713f00 100644
--- a/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
+++ b/net/core/trivial/src/main/java/org/onlab/onos/net/trivial/impl/SimpleDeviceManager.java
@@ -80,20 +80,20 @@
     @Override
     public Device getDevice(DeviceId deviceId) {
         checkNotNull(deviceId, DEVICE_ID_NULL);
-        return null;
+        return store.getDevice(deviceId);
     }
 
     @Override
     public List<Port> getPorts(DeviceId deviceId) {
         checkNotNull(deviceId, DEVICE_ID_NULL);
-        return null;
+        return store.getPorts(deviceId);
     }
 
     @Override
     public Port getPort(DeviceId deviceId, PortNumber portNumber) {
         checkNotNull(deviceId, DEVICE_ID_NULL);
         checkNotNull(portNumber, PORT_NUMBER_NULL);
-        return null;
+        return store.getPort(deviceId, portNumber);
     }
 
     @Override