java如何模拟日历。使用JMockit的getInstance方法？

Question

我正在尝试使用JMockit模拟Calendar.getInstance()方法。这是我第一次嘲笑任何东西

下面是我的方法，它以YYYYMMDD的格式给出最近Monday或最近Thursday的日期

今天是星期天，所以它应该以YYYYMMDD的格式返回星期四的日期，所以它将是2014027

public static String getCorrectDate() {

    Calendar cal = Calendar.getInstance();

    try {
        int dow = cal.get(Calendar.DAY_OF_WEEK);
        switch (dow) {
        case Calendar.THURSDAY:
        case Calendar.FRIDAY:
        case Calendar.SATURDAY:
        case Calendar.SUNDAY:
        while (cal.get(Calendar.DAY_OF_WEEK) != Calendar.THURSDAY) {
            cal.add(Calendar.DATE, -1);
        }
        break;
        case Calendar.MONDAY:
        case Calendar.TUESDAY:
        case Calendar.WEDNESDAY:
        while (cal.get(Calendar.DAY_OF_WEEK) != Calendar.MONDAY) {
            cal.add(Calendar.DATE, -1);
        }
        break;
        }
    } catch (Exception ex) {
        // log error
    }

    return toDateFormat.format(cal.getTime());
}

所以我的问题是，如何使用JMokcit模拟Calendar.getInstance方法，以便轻松地使用junit getCorrectDate方法

我以前从来没有嘲笑过它，所以我面临一些问题

如果可能的话，有人能提供一个简单的例子吗

我试图这样做，但它在MockClass上抱怨我，因为它无法解决。。我还添加了JMockit的maven依赖项

@MockClass(realClass = Calendar.class) 
class CalendarMock {
 private int hour;
 private int day;
 private int minute;

 public CalendarMock(int day, int hour, int minute) {
  this.hour = hour;
  this.day = day;
  this.minute = minute;
 }

 @Mock
 public int get(int id) {
  if (id == Calendar.HOUR_OF_DAY) {
   return hour;
  }
  if (id == Calendar.DAY_OF_WEEK) {
   return day;
  }

  if (id == Calendar.MINUTE) {
   return minute;
  }
  return -1;
 }
}

Answer 1

public class CalendarTest {

    @Test
    public void testCalender() {

        new MockCalendar(1,2,3);

        Calendar c = Calendar.getInstance();
        int day = c.get(Calendar.HOUR_OF_DAY);
        Assert.assertEquals(day, 2);
    }

  public static class MockCalendar extends MockUp<Calendar> {
        private int hour;
        private int minute;
        private int day;

        public MockCalendar(int day, int hour, int minute) {
            this.hour = hour;
            this.minute = minute;
            this.day = day;
        }
        @Mock
        protected void $init() {}

        @Mock
        public static Calendar getInstance() {
            return new GregorianCalendar(1970,1,1);
        }

        @Mock
        public int get(int id) {
            if (id == Calendar.HOUR_OF_DAY) {
                return hour;
            }
            if (id == Calendar.DAY_OF_WEEK) {
                return day;
            }

            if (id == Calendar.MINUTE) {
                return minute;
            }
            return -1;
        }
    }
 }

}

你可以增强做事的逻辑

Answer 2

下面是getCorrectDate()方法的完整测试类（减去导入），使用JMockit 1.6中提供的两个模拟API：

public class DateAdjustmentTest
{
    final int year = 2014;
    final int month = Calendar.MARCH;
    final Calendar[] datesOnDifferentWeekdays = {
        new GregorianCalendar(year, month, 2), // a sunday
        new GregorianCalendar(year, month, 3), // a monday
        new GregorianCalendar(year, month, 4), // a tuesday
        new GregorianCalendar(year, month, 5), // a wednesday
        new GregorianCalendar(year, month, 6), // a thursday
        new GregorianCalendar(year, month, 7), // a friday
        new GregorianCalendar(year, month, 8), // a saturday
    };

    @Test
    public void getAdjustedDateAccordingToWeekday_usingExpectationsAPI()
    {
        new NonStrictExpectations(Calendar.class) {{
            // Each consecutive call to this method will return the next date.
            // Calls to other Calendar methods will not be mocked.
            Calendar.getInstance(); result = datesOnDifferentWeekdays;
        }};

        assertEachDayOfWeekGetsCorrectlyAdjusted();
    }

    void assertEachDayOfWeekGetsCorrectlyAdjusted()
    {
        String thursdayOfPreviousWeek = "27/02/2014";
        assertEquals(thursdayOfPreviousWeek, getCorrectDate());

        String mondayOfSameWeek = "03/03/2014";
        assertEquals(mondayOfSameWeek, getCorrectDate());
        assertEquals(mondayOfSameWeek, getCorrectDate());
        assertEquals(mondayOfSameWeek, getCorrectDate());

        String thursdayOfSameWeek = "06/03/2014";
        assertEquals(thursdayOfSameWeek, getCorrectDate());
        assertEquals(thursdayOfSameWeek, getCorrectDate());
        assertEquals(thursdayOfSameWeek, getCorrectDate());
    }

    @Test
    public void getAdjustedDateAccordingToWeekday_usingMockUpAPI()
    {
        new MockUp<Calendar>() {
            @Mock
            Calendar getInstance(Invocation inv)
            {
                return datesOnDifferentWeekdays[inv.getInvocationIndex()];
            }
        };

        assertEachDayOfWeekGetsCorrectlyAdjusted();
    }
}

我想说这两个测试都非常简单，不需要更改原始的生产代码