java - JUnit テストで何が問題だったのかを知る方法は?

Question

JUnit テストに基づいてコードを修正する必要がありますが、何が問題なのかわかりません。

たとえば、テストコードのこの関数を実行するとエラーが発生しました

@Test
    public void lastValidDay() {
        DayOfWeek dow = new DayOfWeek(12, 31, 2099);
        assertTrue(dow.getDayOfWeek().compareTo("Thursday") == 0);
        assertTrue(dow.getNumericDayOfWeek() == 5);
    }

スムーズに動作するように変更する方法がわかりませんか？これは、これらの異なる JUnit がテストされている私のクラスです。これは、すべてのテストがスムーズに実行されるように変更する必要があるクラスです。

public class DayOfWeek1 {
    int myMonth, myDayOfMonth, myYear, myAdjustment, numericDayOfWeek;
    /*
     * @param what the date was
     */
    public DayOfWeek1(int month, int dayOfMonth, int  year){
        myMonth = month;
        myDayOfMonth = dayOfMonth;
        myYear = year;
    }
    /*
     * @return the numeric day of the week
     */
    public int getNumericDayOfWeek(){
        if(myMonth==1){
            myAdjustment = 1;
            if(myYear%4==0){
                myAdjustment=0;
            }
        }
        if(myMonth==2){
            myAdjustment = 4;
            if(myYear%4==0){
                myAdjustment=3;
            }
        }
        if(myMonth==3){
            myAdjustment = 4;
        }
        if(myMonth==4){
            myAdjustment = 0;
        }
        if(myMonth==5){
            myAdjustment = 2;
        }
        if(myMonth==6){
            myAdjustment = 5;
        }
        if(myMonth==7){
            myAdjustment = 0;
        }
        if(myMonth==8){
            myAdjustment = 3;
        }
        if(myMonth==9){
            myAdjustment = 6;
        }
        if(myMonth==10){
            myAdjustment = 1;
        }
        if(myMonth==11){
            myAdjustment = 4;
        }
        if(myMonth==12){
            myAdjustment = 6;
        }
        int fourDivides = myYear / 4;
        numericDayOfWeek = myAdjustment + myDayOfMonth + (myYear-1900) + fourDivides; 
        return numericDayOfWeek;

    }
    /*
     * returns what day of the week it was
     */
     public String getDayOfWeek(){
         if(numericDayOfWeek==0){
             return "Saturday";
         }
         if(numericDayOfWeek==1){
             return "Sunday";
         }
         if(numericDayOfWeek==2){
             return "Monday";
         }
        if(numericDayOfWeek==3){
             return "Tuesday";
         }
        if(numericDayOfWeek==4){
            return "Wednesday";
         }
        if(numericDayOfWeek==5){
            return "Thursday";
         }
         if(numericDayOfWeek==6){
             return "Friday";
         }
         else{
             return "NO_VALUE";
         }
     }
     /*
      * @return the month in an int
      */
     public int getMonth(){
         return myMonth;
     }
     /*
      * @return the month in a string
      */
     public String getMonthString(){
         if(myMonth==1){
             return "January";
         }
         if(myMonth==2){
             return "February";
         }
         if(myMonth==3){
             return "March";
         }
         if(myMonth==4){
             return "April";
         }
         if(myMonth==5){
             return "May";
         }
         if(myMonth==6){
             return "June";
         }
         if(myMonth==7){
             return "July";
         }
         if(myMonth==8){
             return "August";
         }
         if(myMonth==9){
             return "September";
         }
         if(myMonth==10){
             return "October";
         }
         if(myMonth==11){
             return "November";
         }
         if(myMonth==12){
             return "December";
         }
         else{
             return "NO_VALUE";
         }
     }
     /*
      * @return what day of the month it was
      */
     public int getDayOfMonth(){
         return myDayOfMonth;
     }
     /*
      * @return what year it was
      */
     public int getYear(){
         return myYear;
     }

}

エラーが発生しているコードが正確に何であるかを理解するためのヒントはありますか?