TIll Felix

src_se_annika_stack_Stack.java

package se.annika.stack;

import java.util.ArrayList;

public class Stack {

    private ArrayList<Integer> mainStack, undoStack;
    private Integer mainStackPointer, undoStackPointer;

    public Stack() {
        mainStack = new ArrayList<>();
        undoStack = new ArrayList<>();
        mainStackPointer = mainStack.size() -1;
        undoStackPointer = undoStack.size() -1;
    }


    public void push(Integer i) {
        mainStack.add(i);
        mainStackPointer ++;


    }

    public void pop() {
        pushUndoStack(mainStack.get(mainStackPointer));
        mainStack.remove((int) mainStackPointer);
        mainStackPointer --;
    }

    private void pushUndoStack(Integer removed) {
        undoStackPointer ++;
        undoStack.add(removed);
    }

    public void redo() {
        push(undoStack.get(undoStackPointer));
        undoStackPointer --;
    }

    public ArrayList<Integer> getMainStack() {
        return this.mainStack;
    }


    public Integer getLastRemoval() {

        return undoStack.get(undoStackPointer);
    }

    public Integer getMainStackPointer() {

        return this.mainStackPointer;
    }


}

src_se_annika_stackTests_StackTest.java

package se.annika.stackTests;

import org.junit.*;
import static org.junit.Assert.*;
import se.annika.stack.*;

import java.util.ArrayList;

public class StackTest {

    private static final Integer NUMBER_BIG_ENOUGH = 1000;
    private Stack stack;



    @Before
    public void stackSetup() {
        stack = new Stack();
    }

    public void stackFiller(Integer numberOfIntegers) {
        for (int i = 1; i <= numberOfIntegers; i++) {
            Integer randomInteger = (int) (Math.random() * NUMBER_BIG_ENOUGH + 1);
            stack.push(randomInteger);
        }
    }

    @Test
    public void stackSetUpOK() {
        assertEquals(new ArrayList<Integer>(), stack.getMainStack());
    }

    @Test
    public void addInteger() {
        Integer previousStackSize = stack.getMainStack().size();
        stackFiller(1);

        assertEquals(stack.getMainStack().size(), previousStackSize + 1);
    }


    @Test
    public void removeInteger() {
        stackFiller(1);
        Integer previousStackSize = stack.getMainStack().size();

        stack.pop();
        assertEquals(stack.getMainStack().size(), previousStackSize - 1);
    }

    @Test(expected = ArrayIndexOutOfBoundsException.class)
    public void removeIntegerFromEmptyList() {

        Integer previousStackSize = stack.getMainStack().size();

        stack.pop();
        assertEquals(stack.getMainStack().size(), previousStackSize - 1);
    }

    @Test
    public void undoStackOK() {
        stackFiller(1);
        Integer integerAdded = stack.getMainStack().get(0);
        stack.pop();

        assertEquals(integerAdded, stack.getLastRemoval());
    }

    @Test
    public void redoStackOK() {
        stackFiller(1);
        Integer integerAdded = stack.getMainStack().get(0);
        stack.pop();
        stack.redo();

        assertEquals(integerAdded, stack.getMainStack().get(stack.getMainStackPointer()));
    }
}