junit case

package test;

public class Calculator {

    private static int result; // 静态变量，用于存储运行结果

    public void add(int n) {
        result = result + n;
    }

    public void substract(int n) {
        result = result - 1; // Bug: 正确的应该是 result =result-n
    }

    public void multiply(int n) {

    } // 此方法尚未写好

    public void divide(int n) {
        result = result / n;
    }

    public void square(int n) {
        result = n * n;
    }

    public void squareRoot(int n) {
        for (;;)
            ; // Bug : 死循环
    }

    public void clear() { // 将结果清零
        result = 0;
    }

    public int getResult() {
        return result;
    }
}

package test;

import static org.junit.Assert.*;

import org.junit.Before;
import org.junit.Test;

public class TestCal {

    private static Calculator calculator = new Calculator();
    public void setUp() throws Exception {
        calculator.clear();
    }

    @Test
    public void testAdd() {
        calculator.add(2);
        calculator.add(3);
        assertEquals(5, calculator.getResult());
    }

    @Test
    public void testSubstract() {
        calculator.add(10);
        calculator.substract(2);
        assertEquals(8, calculator.getResult());
    }

    @Test
    public void testMultiply() {
        fail("Not yet implemented");
    }

    @Test
    public void testDivide() {
        calculator.add(8);
        calculator.divide(2);
        assertEquals(4, calculator.getResult());
    }

}