用Junit编写出能判断控制台输出的测试

public class helloWorld {
    public void printHelloWorld() {
        System.out.println("HelloWorld");
    }
}

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

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

import static org.junit.Assert.*;

public class helloWorldTest {
    helloWorld helloWorld = new helloWorld();
    private PrintStream console = null;
    private ByteArrayOutputStream bytes = null;

    @Before
    public void init() {
        bytes = new ByteArrayOutputStream();
        console = System.out;
        System.setOut(new PrintStream(bytes));
    }

    @After
    public void tearDown() {
        System.setOut(console);
    }

    @Test
    public void printHelloWorld() {
        helloWorld.printHelloWorld();
        assertEquals("HelloWorld", bytes.toString().trim());
    }