單元測試怎么模擬多個線程同時操作時的情況呢？結果怎么驗證？

我的方法是啟動多個線程屈嗤，用一個計數(shù)器CountDownLatch去等所有的線程執(zhí)行完了，然后對結果進行校驗吊输。

比如一個list饶号，可能會有多個線程執(zhí)行add方法，那么執(zhí)行完成之后季蚂，將list.size最為結果進行校驗：

    @Test
    public void addStatusChangedListener2() throws InterruptedException {
        final CountDownLatch countDownLatch = new CountDownLatch(1000);
        ExecutorService executorService = Executors.newCachedThreadPool();
        for (int i = 0; i < 1000; i++) {
            executorService.execute(new Runnable() {
                @Override
                public void run() {
                    try {
                        Status.shared().addStatusChangedListener(changedListener);
                    } catch (Exception e) {
                        e.printStackTrace();
                    } finally {
                        countDownLatch.countDown();
                    }
                }
            });
        }
        countDownLatch.await();
        executorService.shutdown();

        assertThat(getListSize(Status.shared(), "mStatusChangeListeners"), is(1000));
    }

其中getListSize是自定義的方法茫船，通過反射方式拿到list的size：

    private int getListSize(Object statusInst, String listName) {
        try {
            Field field = Status.class.getDeclaredField(listName);
            field.setAccessible(true);
            Object futureList = field.get(statusInst);

            Method method = futureList.getClass().getMethod("size");
            return (int) method.invoke(futureList);
        } catch (Exception e) {
            e.printStackTrace();
        }
        //異常情況
        return -1;
    }