Unittest and javadoc.

src/main/java/org/jboss/netty/util/internal/StringUtil.java

@@ -23,12 +23,28 @@
 package org.jboss.netty.util.internal;
 
 /**
+ * String utility class.
+ * 
  * @author The Netty Project (netty-dev@lists.jboss.org)
  * @author Trustin Lee (tlee@redhat.com)
  * @version $Rev$, $Date$
  */
 public class StringUtil {
-
+    
+    private StringUtil() {
+    }
+    
+    /**
+     * Strip an Object of it's ISO control characters. 
+     * 
+     * @param value 
+     *          The Object that should be stripped. This objects toString method will
+     *          called and the result passed to {@link #stripControlCharacters(String)}.
+     * @return {@code String}
+     *          A new String instance with its hexadecimal control characters replaced 
+     *          by a space. Or the unmodified String if it does not contain any ISO 
+     *          controll characters.
+     */
     public static String stripControlCharacters(Object value) {
         if (value == null) {
             return null;
@@ -37,6 +53,16 @@ public class StringUtil {
         return stripControlCharacters(value.toString());
     }
 
+    /**
+     * Strip a String of it's ISO control characters. 
+     * 
+     * @param value 
+     *          The String that should be stripped. 
+     * @return {@code String}
+     *          A new String instance with its hexadecimal control characters replaced 
+     *          by a space. Or the unmodified String if it does not contain any ISO 
+     *          controll characters.
+     */
     public static String stripControlCharacters(String value) {
         if (value == null) {
             return null;

src/test/java/org/jboss/netty/util/internal/StringUtilTest.java

@@ -0,0 +1,93 @@
+/*
+ * JBoss, Home of Professional Open Source
+ * Copyright 2009, Red Hat Middleware LLC, and individual contributors
+ * by the @authors tag. See the copyright.txt in the distribution for a
+ * full listing of individual contributors.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this software; if not, write to the Free
+ * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
+ */
+package org.jboss.netty.util.internal;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+/**
+ * Unit test for {@link StringUtil}.
+ * <p/>
+ * 
+ * @author The Netty Project (netty-dev@lists.jboss.org)
+ * @author Daniel Bevenius (dbevenius@jboss.com)
+ * @version $Rev$, $Date$
+ */
+public class StringUtilTest {
+
+    @Test
+    public void stripControlCharactersObjectNull() {
+        assertNull(StringUtil.stripControlCharacters(null));
+    }
+
+    @Test
+    public void stripControlCharactersNull() {
+        assertNull(StringUtil.stripControlCharacters((String) null));
+    }
+
+    @Test
+    public void stripControlCharactersRightTrim() {
+        final char controlCode = 0x0000;
+        final Object object = "abbb" + controlCode;
+        assertEquals(5, ((String) object).length());
+
+        final String stripped = StringUtil.stripControlCharacters(object);
+        assertFalse(object.equals(stripped));
+        assertEquals(4, stripped.length());
+    }
+
+    @Test
+    public void stripControlCharactersLeftTrim() {
+        final char controlCode = 0x0000;
+        final String string = controlCode + "abbb";
+        assertEquals(5, string.length());
+
+        final String stripped = StringUtil.stripControlCharacters(string);
+        assertFalse(string.equals(stripped));
+        assertEquals(4, stripped.length());
+    }
+
+    @Test
+    public void stripControlCharacters() {
+        for (char i = 0x0000; i <= 0x001F; i ++) {
+            assertStripped(i);
+        }
+        for (char i = 0x007F; i <= 0x009F; i ++) {
+            assertStripped(i);
+        }
+    }
+
+    private void assertStripped(final char controlCode) {
+        final Object object = "aaa" + controlCode + "bbb";
+        final String stripped = StringUtil.stripControlCharacters(object);
+        assertEquals("aaa bbb", stripped);
+    }
+
+    @Test
+    public void stripNonControlCharacter() {
+        final char controlCode = 0x002F;
+        final String string = controlCode + "abbb";
+        final String stripped = StringUtil.stripControlCharacters(string);
+        assertEquals("The string should be unchanged", string, stripped);
+    }
+}