Added more unit tests.
diff --git a/net/api/src/test/java/org/onlab/onos/net/link/LinkEventTest.java b/net/api/src/test/java/org/onlab/onos/net/link/LinkEventTest.java
new file mode 100644
index 0000000..dae9f85
--- /dev/null
+++ b/net/api/src/test/java/org/onlab/onos/net/link/LinkEventTest.java
@@ -0,0 +1,41 @@
+package org.onlab.onos.net.link;
+
+import org.junit.Test;
+import org.onlab.onos.event.AbstractEventTest;
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.DefaultLink;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.provider.ProviderId;
+
+import static org.onlab.onos.net.DeviceId.deviceId;
+import static org.onlab.onos.net.PortNumber.portNumber;
+
+/**
+ * Tests of the device event.
+ */
+public class LinkEventTest extends AbstractEventTest {
+
+    private Link createLink() {
+        return new DefaultLink(new ProviderId("foo"),
+                               new ConnectPoint(deviceId("of:foo"), portNumber(1)),
+                               new ConnectPoint(deviceId("of:bar"), portNumber(2)),
+                               Link.Type.INDIRECT);
+    }
+
+    @Test
+    public void withTime() {
+        Link link = createLink();
+        LinkEvent event = new LinkEvent(LinkEvent.Type.LINK_ADDED, link, 123L);
+        validateEvent(event, LinkEvent.Type.LINK_ADDED, link, 123L);
+    }
+
+    @Test
+    public void withoutTime() {
+        Link link = createLink();
+        long before = System.currentTimeMillis();
+        LinkEvent event = new LinkEvent(LinkEvent.Type.LINK_ADDED, link);
+        long after = System.currentTimeMillis();
+        validateEvent(event, LinkEvent.Type.LINK_ADDED, link, before, after);
+    }
+
+}