public class UnitTest {
     int a;
     int b;
     int answer;//正确答案
     
     public int plus(int a,int b){ 
    	 answer = a + b;
    	 return answer;
 	}
     
     public int minus(int a,int b){
    	 answer = a - b;
    	 return answer;
 	}
     
     public int multiply(int a,int b){
    	 answer = a * b;
    	 return answer;
 	}
     
     public int divide(int a,int b){
    	 answer = a / b;
    	 return answer;
 	}
     
	public int getresult()
	{
		return answer;
	}
	
}

import java.util.*;

public class Expression {
     int a;
     int b;
     static int c;//用户答案
     int answer;//正确答案
     static Scanner in=new Scanner(System.in);
 
     public Expression(){
    	 a = new Random().nextInt()%10;
    	 b = new Random().nextInt()%10;
    	 System.out.print(""+a+"+"+b+"=");
 	 }
     
    public static void main(String[] args){
	int answer;
	Expression expression = new Expression();
	UnitTest u = new UnitTest();
	answer = u.plus(expression.a, expression.b);
	try{
		Expression.c = in.nextInt();
	}
	catch(InputMismatchException e)
	{   
		System.err.println("\nError  ,please Enter a Int number");
	}
	if(answer==c)
	{
		System.out.print("答对了");
	}
	else{
		System.out.println("答错了");
		System.out.println("the answer is "+answer);
	}
　　}
}

import static org.junit.Assert.*;

import org.junit.Test;

public class UnitTestTest {

	public static UnitTest puls = new UnitTest();
	public static int answer;
	
	@Test
	public void testPlus() {
		puls.plus(1,1);
		assertEquals(2, puls.getresult());
	}

	@Test
	public void testMinus() {
		puls.minus(1,1);
		assertEquals(0, puls.getresult());
	}

	@Test
	public void testMultiply() {
		puls.multiply(1,1);
		assertEquals(1, puls.getresult());
	}
	
	@Test(expected=ArithmeticException.class)
	public void testDivide1(){
	    puls.divide(1, 0);
	}

	@Test
	public void testDivide() {
		puls.divide(1,1);
		assertEquals(1, puls.getresult());
	}

}