diff --git a/common/source/java/ch/systemsx/cisd/common/test/AssertionUtil.java b/common/source/java/ch/systemsx/cisd/common/test/AssertionUtil.java
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+++ b/common/source/java/ch/systemsx/cisd/common/test/AssertionUtil.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2008 ETH Zuerich, CISD
+ *
+ * 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 ch.systemsx.cisd.common.test;
+
+import org.testng.AssertJUnit;
+
+/**
+ * Utilities for making assertions in unit tests.
+ * 
+ * @author Tomasz Pylak
+ */
+public class AssertionUtil
+{
+    /** asserts that given text contains expectedSubstring */
+    public static void assertContains(String expectedSubstring, String text)
+    {
+        String errorMsg =
+                String.format("String '%s' was expected to be a substring of '%s'.",
+                        expectedSubstring, text);
+        AssertJUnit.assertTrue(errorMsg, text.contains(expectedSubstring));
+    }
+
+}