使用IsEmpty和isFullJUnit测试来测试堆栈是否为空/已满

问题描述

我正在尝试编写一个isEmpty（）和isFull（）方法，以检查堆栈是否为空或其中是否有值。我不确定如何编写方法，以便所有测试均成功返回。这是类和方法的代码：

public class stack {
    
    private int top;  
    private int maxSize; 
    private String stackItems[]; 
    
    //default no-args constructor
    public stack() {
        this.maxSize = 5; 
        this.top = -1; 
        this.stackItems = new String[maxSize];
    }
    
    //allows you to set the max size of the stack
    public stack(int maxSize) {
        this.maxSize = maxSize;
        this.top = -1; 
        this.stackItems = new String[maxSize];
    }
    
    //I have two tests for this method: testIsFullFalse and testIsFullTrue
    public boolean isFull() {
        return top == maxSize -1; 
    }

    //Two tests for this method: testIsEmptyFalse and testIsEmptyTrue
    public boolean isEmpty() {
        // In progress  
        return top != maxSize -1;
    }

以下是测试：

    @Test
    void testIsEmptyTrue() {
        // ARRANGE
        stack myStack = new stack(1);
        boolean actual,expected;
        // ACT
        actual = myStack.isEmpty();
        expected = true;
        // ASSERT
        assertEquals(expected,actual);
    }

    @Test
    void testIsEmptyFalse() throws StackFullException {
        // ARRANGE
        stack myStack = new stack(1);
        String item = "Java is Fun!";
        boolean actual,expected;
        // ACT
        myStack.push(item);
        actual = myStack.isEmpty();
        expected = false;
        // ASSERT
        assertEquals(expected,actual);
    }

    @Test
    void testIsFullTrue() throws StackFullException {
        // ARRANGE
        stack myStack = new stack(1);
        String item = "testing";
        boolean actual,expected;
        // ACT
        myStack.push(item);
        actual = myStack.isFull();
        expected = true;
        // ASSERT
        assertEquals(expected,actual);
    }

    @Test
    void testIsFullFalse() throws StackFullException {
        // ARRANGE
        stack myStack = new stack(1);
        boolean actual,expected;
        // ACT
        actual = myStack.isFull();
        expected = false;
        // ASSERT
        assertEquals(expected,actual);
    }

现在，testIsEmptyTrue（）和testIsFullFalse（）返回成功，而testIsEmptyFalse（）和testIsFullTrue（）返回失败。我希望他们都作为成功回来。关于如何修复方法的任何指示？

解决方法

有点困难，没有看到push方法，但是问题可能出在这里：

//Two tests for this method: testIsEmptyFalse and testIsEmptyTrue
public boolean isEmpty() {
    // In progress  
    return top != maxSize -1;
}

除非isEmpty() 等于top，否则maxSize -1方法将始终返回true。

对于名为“ isEmpty”的方法，这样的事情怎么样：

private static final int bottom = -1;
private int top = bottom;  
private int maxSize; 
private String stackItems[]; 

//default no-args constructor
public stack() {
    this.maxSize = 5; 
    //this.top = -1; 
    this.stackItems = new String[maxSize];
}

//allows you to set the max size of the stack
public stack(int maxSize) {
    this.maxSize = maxSize;
    //this.top = -1; 
    this.stackItems = new String[maxSize];
}

...

//Two tests for this method: testIsEmptyFalse and testIsEmptyTrue
public boolean isEmpty() {
    // In progress  
    return top == bottom;
}