非确定性行为的断言

Question

@Test/*(expected=ArrayIndexOutOfBoundsException.class)*/
public void raceConditions() throws Exception {


    List<String> strings = new ArrayList<>(); //not thread-safe

    Stream.iterate("+", s -> s+"+")
    .parallel()
    .limit(10000)
    //.peek(e -> System.out.println(e+" is processed by "+ Thread.currentThread().getName()))
    .forEach(e -> strings.add(e));

    System.out.println("# of elems: "+strings.size());
} 

或者也许有更好的框架专门为这类场景设计？

谢了。

Answer 1

我不确定这是否是你真正想要的，但你可以尝试使用假设。在执行测试中的代码后，对结果执行一个假设，只有在假设正确的情况下，下面的代码/断言才会执行。

由于3.9.0 AssertJ提供了开箱即用的假设，例如：

List<String> strings = new ArrayList<>(); // not thread-safe

int requestedSize = 10_000;

Throwable thrown = catchThrowable(() -> {
  Stream.iterate("+", s -> s + "+")
        .parallel()
        .limit(requestedSize)
        .forEach(strings::add);
});

// thrown is null if there was no exception raised
assumeThat(thrown).isNotNull();

// only executed if thrown was not null otherwise the test is skipped.
assertThat(thrown).isInstanceOf(ArrayIndexOutOfBoundsException.class);

如果测试异步代码，还应该查看https://github.com/awaitility/awaitility。