### Question:
StringUtil { public static String unescapeString(String escapedString) { Matcher match = escapeSequence.matcher(escapedString); StringBuffer output = new StringBuffer(); while(match.find()) { match.appendReplacement(output, substitution(match.group())); } match.appendTail(output); return output.toString(); } private  StringUtil(); static String unquote(String quotedString); static String unescapeString(String escapedString); static List<Object> parseCSVLine(String line, String separatorRegex); static final String STRING_ESCAPE_SEQUENCE_REGEX; static final String QUOTED_STRING_REGEX; static final String SINGLEQUOTED_STRING_REGEX; static final String DOUBLE_REGEX; static final String DOUBLE_REGEX_WITH_NAN; }### Answer:
@Test public void unescapeString1() { assertThat(StringUtil.unescapeString("\\\""), equalTo("\"")); assertThat(StringUtil.unescapeString("\\\"hello\\\""), equalTo("\"hello\"")); }
@Test public void unescapeString2() { assertThat(StringUtil.unescapeString("\\\\"), equalTo("\\")); assertThat(StringUtil.unescapeString("path\\\\to\\\\file"), equalTo("path\\to\\file")); }
@Test public void unescapeString3() { assertThat(StringUtil.unescapeString("\\\'"), equalTo("\'")); assertThat(StringUtil.unescapeString("That\\\'s right!"), equalTo("That\'s right!")); }
@Test public void unescapeString4() { assertThat(StringUtil.unescapeString("\\r"), equalTo("\r")); assertThat(StringUtil.unescapeString("This\\rThat"), equalTo("This\rThat")); }
@Test public void unescapeString5() { assertThat(StringUtil.unescapeString("\\n"), equalTo("\n")); assertThat(StringUtil.unescapeString("This\\nThat"), equalTo("This\nThat")); }
@Test public void unescapeString6() { assertThat(StringUtil.unescapeString("\\b"), equalTo("\b")); assertThat(StringUtil.unescapeString("Back\\bspace"), equalTo("Back\bspace")); }
@Test public void unescapeString7() { assertThat(StringUtil.unescapeString("\\t"), equalTo("\t")); assertThat(StringUtil.unescapeString("Column one\\tColumn two"), equalTo("Column one\tColumn two")); }
@Test public void unescapeString8() { assertThat(StringUtil.unescapeString("\\u0061"), equalTo("\u0061")); assertThat(StringUtil.unescapeString("Th\\u0061t is w\\u006fnderfu\\u006C!"), equalTo("That is wonderful!")); }
@Test public void unescapeString9() { assertThat(StringUtil.unescapeString("\\141"), equalTo("\141")); assertThat(StringUtil.unescapeString("L\\141st \\612"), equalTo("Last 12")); }