Index: /trunk/EventBenchCore/src/de/ugoe/cs/eventbench/assertions/FileEqualsReplay.java
===================================================================
--- /trunk/EventBenchCore/src/de/ugoe/cs/eventbench/assertions/FileEqualsReplay.java	(revision 339)
+++ /trunk/EventBenchCore/src/de/ugoe/cs/eventbench/assertions/FileEqualsReplay.java	(revision 340)
@@ -1,3 +1,5 @@
 package de.ugoe.cs.eventbench.assertions;
+
+import java.security.InvalidParameterException;
 
 import de.ugoe.cs.eventbench.data.IReplayable;
@@ -19,5 +21,5 @@
 	 * </p>
 	 */
-	String actualFile = null;
+	protected final String actualFile;
 
 	/**
@@ -26,5 +28,5 @@
 	 * </p>
 	 */
-	String expectedFile = null;
+	protected final String expectedFile;
 
 	/**
@@ -44,6 +46,15 @@
 	 * @param actualFile
 	 *            name and path of the actual file
+	 * @throws InvalidParameterException
+	 *             thrown if expectedFile or actualFile are null
 	 */
 	public FileEqualsReplay(String expectedFile, String actualFile) {
+		if (expectedFile == null) {
+			throw new InvalidParameterException(
+					"expected file must not be null");
+		}
+		if (actualFile == null) {
+			throw new InvalidParameterException("actual file must not be null");
+		}
 		this.expectedFile = expectedFile;
 		this.actualFile = actualFile;
@@ -57,11 +68,11 @@
 	public String getReplay() {
 
-		actualFile = StringTools.xmlEntityReplacement(actualFile);
-		expectedFile = StringTools.xmlEntityReplacement(expectedFile);
+		String actualFileTmp = StringTools.xmlEntityReplacement(actualFile);
+		String expectedFileTmp = StringTools.xmlEntityReplacement(expectedFile);
 
 		StringBuilder currentMsgStr = new StringBuilder(800);
 		currentMsgStr.append("  <fileEquals ");
-		currentMsgStr.append("actualFile=\"" + actualFile + "\" ");
-		currentMsgStr.append("expectedFile=\"" + expectedFile + "\"/>");
+		currentMsgStr.append("actualFile=\"" + actualFileTmp + "\" ");
+		currentMsgStr.append("expectedFile=\"" + expectedFileTmp + "\"/>");
 		currentMsgStr.append(StringTools.ENDLINE);
 		return currentMsgStr.toString();
Index: /trunk/EventBenchCore/src/de/ugoe/cs/eventbench/assertions/TextEqualsReplay.java
===================================================================
--- /trunk/EventBenchCore/src/de/ugoe/cs/eventbench/assertions/TextEqualsReplay.java	(revision 339)
+++ /trunk/EventBenchCore/src/de/ugoe/cs/eventbench/assertions/TextEqualsReplay.java	(revision 340)
@@ -1,3 +1,5 @@
 package de.ugoe.cs.eventbench.assertions;
+
+import java.security.InvalidParameterException;
 
 import de.ugoe.cs.eventbench.data.IReplayable;
@@ -19,5 +21,5 @@
 	 * </p>
 	 */
-	private String expectedValue;
+	protected final String expectedValue;
 
 	/**
@@ -26,5 +28,5 @@
 	 * </p>
 	 */
-	private String target;
+	protected final String target;
 
 	/**
@@ -35,5 +37,20 @@
 	private static final long serialVersionUID = 1L;
 
+	/**
+	 * <p>
+	 * Constructor. Creates a new TextEqualsReplay.
+	 * 
+	 * @param expectedValue
+	 *            expected string value
+	 * @param target
+	 *            string description of the target whose string value is
+	 *            compared to the expected value
+	 * @throws InvalidParameterException
+	 *             thrown if target is null
+	 */
 	public TextEqualsReplay(String expectedValue, String target) {
+		if (target == null) {
+			throw new InvalidParameterException("target must not be null");
+		}
 		this.expectedValue = expectedValue;
 		this.target = target;
@@ -48,8 +65,8 @@
 	public String getReplay() {
 
-		expectedValue = StringTools.xmlEntityReplacement(expectedValue);
+		String expectedValueTmp = StringTools.xmlEntityReplacement(expectedValue);
 
 		StringBuilder currentMsgStr = new StringBuilder(400);
-		currentMsgStr.append(" <textEquals expectedValue=\"" + expectedValue
+		currentMsgStr.append(" <textEquals expectedValue=\"" + expectedValueTmp
 				+ "\">");
 		currentMsgStr.append(StringTools.ENDLINE);