给你一个函数nextday，请分别用语句覆盖、判定覆盖、条件覆盖、判定条件覆盖、条件组合覆盖设计测试用例，并编写对应Junit代码进行测试

语句覆盖设计测试用例：

@Test
public void testNextDay() {
   assertEquals("2022-01-02", nextday("2022-01-01"));
}

判定覆盖设计测试用例：

@Test
public void testNextDay() {
   assertEquals("2022-01-02", nextday("2022-01-01"));
   assertEquals("输入日期格式不正确", nextday("2022/01/01"));
}

条件覆盖设计测试用例：

@Test
public void testNextDay() {
   assertEquals("2022-01-02", nextday("2022-01-01"));
   assertEquals("输入日期格式不正确", nextday("2022/01/01"));
   assertEquals("输入日期不存在", nextday("2022-02-31"));
}

判定条件覆盖设计测试用例：

@Test
public void testNextDay() {
   assertEquals("2022-01-02", nextday("2022-01-01"));
   assertEquals("输入日期格式不正确", nextday("2022/01/01"));
   assertEquals("输入日期不存在", nextday("2022-02-31"));
   assertEquals("输入日期不合法", nextday("2022-13-01"));
}

条件组合覆盖设计测试用例：

@Test
public void testNextDay() {
   assertEquals("2022-01-02", nextday("2022-01-01"));
   assertEquals("输入日期格式不正确", nextday("2022/01/01"));
   assertEquals("输入日期不存在", nextday("2022-02-31"));
   assertEquals("输入日期不合法", nextday("2022-13-01"));
   assertEquals("2022-02-01", nextday("2022-01-31"));
}

对应Junit代码：

public String nextday(String date) {
   String[] dates = date.split("-");
   int year, month, day;
   try {
      year = Integer.parseInt(dates[0]);
      month = Integer.parseInt(dates[1]);
      day = Integer.parseInt(dates[2]);
   } catch (NumberFormatException e) {
      return "输入日期格式不正确";
   }
   if (month < 1 || month > 12) {
      return "输入日期不合法";
   }
   if (day < 1 || day > 31) {
      return "输入日期不合法";
   }
   if ((month == 4 || month == 6 || month == 9 || month == 11) && day == 31) {
      return "输入日期不存在";
   }
   if (month == 2) {
      if (day == 29 && !(year % 4 == 0 && year % 100 != 0 || year % 400 == 0)) {
         return "输入日期不存在";
      }
      if (day > 29) {
         return "输入日期不存在";
      }
   }
   day++;
   if (day > getMonthMaxDay(year, month)) {
      day = 1;
      month++;
      if (month > 12) {
         month = 1;
         year++;
      }
   }
   return String.format("%04d-%02d-%02d", year, month, day);
}

private int getMonthMaxDay(int year, int month) {
   if (month == 2) {
      return year % 4 == 0 && year % 100 != 0 || year % 400 == 0 ? 29 : 28;
   }
   if (month == 4 || month == 6 || month == 9 || month == 11) {
      return 30;
   }
   return 31;
}