如何编写多线程单元测试？

import org.junit.Test;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import static org.junit.Assert.assertEquals;

public class MyMultiThreadedTest {

    @Test
    public void testMultiThreaded() throws InterruptedException {
        ExecutorService executorService = Executors.newFixedThreadPool(2);
        CountDownLatch latch = new CountDownLatch(2);

        MyThreadSafeClass myThreadSafeClass = new MyThreadSafeClass();

        executorService.execute(() -> {
            myThreadSafeClass.incrementCounter();
            latch.countDown();
        });

        executorService.execute(() -> {
            myThreadSafeClass.incrementCounter();
            latch.countDown();
        });

        latch.await();
        assertEquals(2, myThreadSafeClass.getCounter());
    }

    private class MyThreadSafeClass {
        private int counter = 0;
        private final Object lock = new Object();

        public void incrementCounter() {
            synchronized (lock) {
                counter++;
            }
        }

        public int getCounter() {
            return counter;
        }
    }
}