Made discovery more reliable & added docs/tests

- Added unit tests
- Added documentation for discovery classes
- Improved error handling

Tags: #story[1281]

src/test/java/seng302/serverDiscovery/ServerTableTest.java

@@ -0,0 +1,57 @@
+package seng302.serverDiscovery;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+import seng302.discoveryServer.util.ServerListing;
+import seng302.discoveryServer.util.ServerTable;
+
+import java.util.Objects;
+
+import static org.junit.Assert.assertTrue;
+
+public class ServerTableTest {
+    private static ServerTable serverTable;
+
+    @BeforeClass
+    public static void setup(){
+        serverTable = new ServerTable();
+    }
+
+    @Test
+    public void testAddServer(){
+        ServerListing listing = new ServerListing("", "", "", 12, 12);
+        serverTable.addServer(listing);
+
+        assertTrue(serverTable.getAllServers().contains(listing));
+    }
+
+    @Test
+    public void testGetNextRoomCodeIsUnique(){
+        assertTrue(!Objects.equals(serverTable.getNextRoomCode(), serverTable.getNextRoomCode()));
+    }
+
+    @Test
+    public void testGetServerRoomCode(){
+        ServerListing listing = new ServerListing("123", "", "", 12, 12);
+        listing.setRoomCode(serverTable.getNextRoomCode().toString());
+        serverTable.addServer(listing);
+
+        ServerListing result = serverTable.getServerByRoomCode(listing.getRoomCode());
+
+        assertTrue(result.equals(listing));
+    }
+
+    @Test
+    public void testServersRemovedOnExpiry() throws InterruptedException {
+        ServerListing listing = new ServerListing("432", "221", "", 12, 12);
+        listing.setTtl(1);
+
+        serverTable.addServer(listing);
+
+        listing.decrementTtl();
+
+        Thread.sleep(1000);
+
+        assertTrue(!serverTable.getAllServers().contains(listing));
+    }
+}