Added test for StartupSettings and documentation of use - in README.md.

* Also tweaked the `StartupSettings` so that it now reads in an `id` for the node, rather than just resulting in a blank `id`;
* Moved some logging from stdout to log4j
* Full `maven test` passing

Arguably this would result in a version change, as the settings file format has changed and now requires an id field. However we could make it optional, but it seems odd to have nodes with no ids.

src/test/java/io/teknek/gossip/StartupSettingsTest.java

@@ -0,0 +1,79 @@
+package io.teknek.gossip;
+
+import com.google.code.gossip.GossipMember;
+import com.google.code.gossip.GossipService;
+import com.google.code.gossip.GossipSettings;
+import com.google.code.gossip.StartupSettings;
+import org.apache.log4j.Logger;
+import org.json.JSONException;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Tests support of using {@code StartupSettings} and thereby reading
+ * setup config from file.
+ */
+public class StartupSettingsTest {
+  private static final Logger log = Logger.getLogger( StartupSettingsTest.class );
+
+  @Test
+  public void testUsingSettingsFile() throws IOException, InterruptedException, JSONException {
+    File settingsFile = File.createTempFile("gossipTest",".json");
+    log.debug( "Using settings file: " + settingsFile.getAbsolutePath() );
+    settingsFile.deleteOnExit();
+    writeSettingsFile(settingsFile);
+
+    // Start the other simple node that the settings file points to
+    GossipService firstService = new GossipService(
+      "127.0.0.1", 50000, UUID.randomUUID().toString(),
+      new ArrayList<GossipMember>(), new GossipSettings(), null
+    );
+    firstService.start();
+
+    // Start a node with the settings file
+    GossipService serviceUnderTest = new GossipService(
+      StartupSettings.fromJSONFile( settingsFile )
+    );
+    serviceUnderTest.start();
+
+    // Let the sync up
+    TimeUnit.SECONDS.sleep(2);
+
+    // Check the results
+    assertEquals(1, firstService.get_gossipManager().getMemberList().size() );
+    assertEquals(1, serviceUnderTest.get_gossipManager().getMemberList().size() );
+    assertTrue(
+      firstService.get_gossipManager().getMemberList().size() ==
+      serviceUnderTest.get_gossipManager().getMemberList().size() );
+
+    firstService.shutdown();
+    serviceUnderTest.shutdown();
+  }
+
+  private void writeSettingsFile( File target ) throws IOException {
+    String settings =
+            "[{\n" + // It is odd that this is meant to be in an array, but oh well.
+            "  \"id\":\"" + UUID.randomUUID() + "\",\n" +
+            "  \"port\":50001,\n" +
+            "  \"gossip_interval\":1000,\n" +
+            "  \"cleanup_interval\":10000,\n" +
+            "  \"members\":[\n" +
+            "    {\"host\":\"127.0.0.1\", \"port\":50000}\n" +
+            "  ]\n" +
+            "}]";
+
+    log.info( "Using settings file with contents of:\n---\n" + settings + "\n---" );
+    FileOutputStream output = new FileOutputStream(target);
+    output.write( settings.getBytes() );
+    output.close();
+  }
+}

src/test/java/io/teknek/gossip/TenNodeThreeSeedTest.java

@@ -52,11 +52,12 @@ public class TenNodeThreeSeedTest {
               new GossipListener(){
         @Override
         public void gossipEvent(GossipMember member, GossipState state) {
-          System.out.println(member+" "+ state);
+          log.info(member+" "+ state);
         }
       });
       clients.add(gossipService);
       gossipService.start();
+      gossipService.get_gossipManager().getMemberList();
     }
     TUnit.assertThat(new Callable<Integer> (){
       public Integer call() throws Exception {