### Question:
FunctionExpressionFactory { public static Expression currentDate() { return new ASTCurrentDate(); }  static Expression substringExp(Expression exp, int offset, int length); static Expression substringExp(String path, int offset, int length); static Expression substringExp(Expression exp, Expression offset, Expression length); static Expression trimExp(Expression exp); static Expression trimExp(String path); static Expression lowerExp(Expression exp); static Expression lowerExp(String path); static Expression upperExp(Expression exp); static Expression upperExp(String path); static Expression lengthExp(Expression exp); static Expression lengthExp(String path); static Expression locateExp(String substring, Expression exp); static Expression locateExp(String substring, String path); static Expression locateExp(Expression substring, Expression exp); static Expression absExp(Expression exp); static Expression absExp(String path); static Expression sqrtExp(Expression exp); static Expression sqrtExp(String path); static Expression modExp(Expression exp, Number number); static Expression modExp(String path, Number number); static Expression modExp(Expression exp, Expression number); static Expression concatExp(Expression... expressions); static Expression concatExp(String... paths); static Expression countExp(); static Expression countExp(Expression exp); static Expression countDistinctExp(Expression exp); static Expression minExp(Expression exp); static Expression maxExp(Expression exp); static Expression avgExp(Expression exp); static Expression sumExp(Expression exp); static Expression currentDate(); static Expression currentTime(); static Expression currentTimestamp(); static Expression yearExp(Expression exp); static Expression yearExp(String path); static Expression monthExp(Expression exp); static Expression monthExp(String path); static Expression weekExp(Expression exp); static Expression weekExp(String path); static Expression dayOfYearExp(Expression exp); static Expression dayOfYearExp(String path); static Expression dayOfMonthExp(Expression exp); static Expression dayOfMonthExp(String path); static Expression dayOfWeekExp(Expression exp); static Expression dayOfWeekExp(String path); static Expression hourExp(Expression exp); static Expression hourExp(String path); static Expression minuteExp(Expression exp); static Expression minuteExp(String path); static Expression secondExp(Expression exp); static Expression secondExp(String path); static Expression functionCall(String function, Object... args); static Expression operator(String operator, Object... args);  }### Answer:
@Test public void currentDateTest() throws Exception { Expression exp = FunctionExpressionFactory.currentDate(); assertTrue(exp instanceof ASTCurrentDate); }