diff --git a/src/test/java/kieker/diagnosis/common/model/PropertiesModelTest.java b/src/test/java/kieker/diagnosis/common/model/PropertiesModelTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..38729267b4d0d8ea904dc359db2115b8fd9bace0
--- /dev/null
+++ b/src/test/java/kieker/diagnosis/common/model/PropertiesModelTest.java
@@ -0,0 +1,81 @@
+/***************************************************************************
+ * Copyright 2014 Kieker Project (http://kieker-monitoring.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ ***************************************************************************/
+
+package kieker.diagnosis.common.model;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+import java.util.Observable;
+import java.util.Observer;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Test;
+
+public final class PropertiesModelTest {
+
+	@Test
+	public void transactionalSettingShouldWork() {
+		final BooleanObserver observer = new BooleanObserver();
+		final PropertiesModel model = new PropertiesModel();
+		model.addObserver(observer);
+
+		model.startModification();
+
+		model.setTimeunit(TimeUnit.NANOSECONDS);
+		assertThat(observer.isFlag(), is(false));
+
+		model.commitModification();
+
+		assertThat(observer.isFlag(), is(true));
+	}
+
+	@Test
+	public void usualSettingShouldNotifyObservers() {
+		final BooleanObserver observer = new BooleanObserver();
+		final PropertiesModel model = new PropertiesModel();
+		model.addObserver(observer);
+
+		model.setTimeunit(TimeUnit.NANOSECONDS);
+		assertThat(observer.isFlag(), is(true));
+	}
+
+	@Test
+	public void settingShouldBePersisted() {
+		final PropertiesModel fstModel = new PropertiesModel();
+		fstModel.setTimeunit(TimeUnit.NANOSECONDS);
+		fstModel.setTimeunit(TimeUnit.MICROSECONDS);
+
+		final PropertiesModel sndModel = new PropertiesModel();
+		assertThat(sndModel.getTimeunit(), is(TimeUnit.MICROSECONDS));
+	}
+
+	private static class BooleanObserver implements Observer {
+
+		private boolean flag = false;
+
+		@Override
+		public void update(final Observable o, final Object arg) {
+			this.flag = true;
+		}
+
+		public boolean isFlag() {
+			return this.flag;
+		}
+
+	}
+
+}
diff --git a/src/test/java/kieker/diagnosis/common/model/importer/stages/AggregatedTraceStatisticsDecoratorTest.java b/src/test/java/kieker/diagnosis/common/model/importer/stages/AggregatedTraceStatisticsDecoratorTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..68aa8e7415143bbd5caecdd8d2e24c1e8efb0a14
--- /dev/null
+++ b/src/test/java/kieker/diagnosis/common/model/importer/stages/AggregatedTraceStatisticsDecoratorTest.java
@@ -0,0 +1,59 @@
+/***************************************************************************
+ * Copyright 2014 Kieker Project (http://kieker-monitoring.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ ***************************************************************************/
+
+package kieker.diagnosis.common.model.importer.stages;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+import java.util.Arrays;
+
+import kieker.diagnosis.common.domain.AggregatedTrace;
+import kieker.diagnosis.common.domain.OperationCall;
+import kieker.diagnosis.common.domain.Trace;
+
+import org.junit.Test;
+
+public final class AggregatedTraceStatisticsDecoratorTest {
+
+	@Test
+	public void minMaxMeanAndAvgCalculationForSingleCallShouldWork() throws Exception {
+		final OperationCall call1 = new OperationCall("", "", "", 43);
+		final OperationCall call2 = new OperationCall("", "", "", 44);
+		final OperationCall call3 = new OperationCall("", "", "", 45);
+
+		call1.setDuration(15);
+		call2.setDuration(7);
+		call3.setDuration(44);
+
+		final Trace trace1 = new Trace(call1, 43);
+		final Trace trace2 = new Trace(call2, 44);
+		final Trace trace3 = new Trace(call3, 45);
+
+		final AggregatedTrace trace = new AggregatedTrace(Arrays.asList(trace1, trace2, trace3));
+
+		final AggregatedTraceStatisticsDecorator decorator = new AggregatedTraceStatisticsDecorator();
+
+		decorator.onStarting();
+		decorator.execute(trace);
+
+		assertThat(trace.getRootOperationCall().getMinDuration(), is(7L));
+		assertThat(trace.getRootOperationCall().getMaxDuration(), is(44L));
+		assertThat(trace.getRootOperationCall().getAvgDuration(), is(22L));
+		assertThat(trace.getRootOperationCall().getMeanDuration(), is(15L));
+	}
+
+}
diff --git a/src/test/java/kieker/diagnosis/common/model/importer/stages/TraceStatisticsDecoratorTest.java b/src/test/java/kieker/diagnosis/common/model/importer/stages/TraceStatisticsDecoratorTest.java
index f656acaf29442e269edc9f89e79641b5cb205fb9..7234e2a07b52084551f7f7da7c7311d7bd1b1ea9 100644
--- a/src/test/java/kieker/diagnosis/common/model/importer/stages/TraceStatisticsDecoratorTest.java
+++ b/src/test/java/kieker/diagnosis/common/model/importer/stages/TraceStatisticsDecoratorTest.java
@@ -24,7 +24,7 @@ import kieker.diagnosis.common.domain.Trace;
 
 import org.junit.Test;
 
-public class TraceStatisticsDecoratorTest {
+public final class TraceStatisticsDecoratorTest {
 
 	@Test
 	public void percentCalculationShouldWork() throws Exception {