Array and its Derived List in Java

ArrayAndArraysAsListTest.java

package com.ffbit.collections;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

import java.util.Arrays;
import java.util.List;

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

public class ArrayAndArraysAsListTest {
    private List<Integer> list;
    private Integer[] array;

    @Before
    public void setUp() {
        array = new Integer[] { 1, 2 };
        list = Arrays.asList(array);
    }

    @Test(expected = UnsupportedOperationException.class)
    public void itShouldThrowExceptionWhenModified() throws Exception {
        list.add(3);
    }

    @Test
    public void itShouldChangeUnderlyingArray() throws Exception {
        list.set(0, 3);

        assertThat(array, is(list.toArray(new Integer[] {})));
    }

    @Test
    public void itShouldChangeDerivedList() throws Exception {
        array[0] = 3;

        assertThat(array, is(list.toArray(new Integer[] {})));
    }

}