### Question:
Utils { static String toDebugString(final byte[] bytes, final int len, final Charset charset) { if (charset == null) { return toDebugString(new String(bytes, 0, len, Charset.defaultCharset())); } return toDebugString(new String(bytes, 0, len, charset)); } private  Utils();   }### Answer:
@Test public void testDebugString() { assertEquals(toDebugString(null), "null"); assertEquals(toDebugString((Object) null), "null"); assertEquals(toDebugString("ABC"), "ABC"); final char[] chars = new char[1000]; Arrays.fill(chars, 'x'); final int length = toDebugString(String.valueOf(chars)).length(); assertEquals(length, Utils.MAX_STRING_LENGTH + 22); assertEquals(toDebugString("ab\n\r"), "ab\\n\\r"); final String utfString = toDebugString("abcdef".getBytes(), 4, Charsets.UTF_16); assertEquals(utfString.length(), 2); final String defaultStirng = toDebugString("abcdef".getBytes(), 3, null); assertEquals(defaultStirng, "abc"); }