Use Log4J pattern to generate collection name, fix for test data cleanup.

spring-data-mongodb-log4j/src/test/java/org/springframework/data/document/mongodb/log4j/AppenderTest.java

@@ -20,6 +20,7 @@ import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
 import java.net.UnknownHostException;
+import java.util.Calendar;
 
 import com.mongodb.DB;
 import com.mongodb.DBCursor;
@@ -38,13 +39,16 @@ public class AppenderTest {
   private Logger log = Logger.getLogger(NAME);
   private Mongo mongo;
   private DB db;
+  private String collection;
 
   @Before
   public void setup() {
     try {
       mongo = new Mongo("localhost", 27017);
       db = mongo.getDB("logs");
-      db.getCollection(NAME).drop();
+      Calendar now = Calendar.getInstance();
+      collection = String.valueOf(now.get(Calendar.YEAR)) + String.format("%1$02d", now.get(Calendar.MONTH) + 1);
+      db.getCollection(collection).drop();
     } catch (UnknownHostException e) {
       throw new RuntimeException(e.getMessage(), e);
     }
@@ -57,7 +61,7 @@ public class AppenderTest {
     log.warn("WARN message");
     log.error("ERROR message");
 
-    DBCursor msgs = db.getCollection(NAME).find();
+    DBCursor msgs = db.getCollection(collection).find();
     assertThat(msgs.count(), is(4));
 
   }

spring-data-mongodb-log4j/src/test/resources/log4j.properties

@@ -6,7 +6,7 @@ log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - <%m>%n
 log4j.appender.stdout.host = localhost
 log4j.appender.stdout.port = 27017
 log4j.appender.stdout.database = logs
-log4j.appender.stdout.collection = %1$4d%2$02d%3$02d
+log4j.appender.stdout.collectionPattern = %X{year}%X{month}
 log4j.appender.stdout.applicationId = my.application
 log4j.appender.stdout.warnOrHigherWriteConcern = FSYNC_SAFE