线程中的junit断言抛出异常 [英] junit assert in thread throws exception

问题描述

如果抛出异常而不是显示失败，或者我是否应该在线程内部没有断言，我做错了什么？

What am I doing wrong that an exception is thrown instead of showing a failure, or should I not have assertions inside threads?

 @Test
 public void testComplex() throws InterruptedException {
  int loops = 10;
  for (int i = 0; i < loops; i++) {
   final int j = i;
   new Thread() {
    @Override
    public void run() {
     ApiProxy.setEnvironmentForCurrentThread(env);//ignore this
     new CounterFactory().getCounter("test").increment();//ignore this too
     int count2 = new CounterFactory().getCounter("test").getCount();//ignore
     assertEquals(j, count2);//here be exceptions thrown. this is line 75
    }
   }.start();
  }
  Thread.sleep(5 * 1000);
  assertEquals(loops, new CounterFactory().getCounter("test").getCount());
}

StackTrace

StackTrace

Exception in thread "Thread-26" junit.framework.AssertionFailedError: expected:<5> but was:<6>
    at junit.framework.Assert.fail(Assert.java:47)
    at junit.framework.Assert.failNotEquals(Assert.java:277)
    at junit.framework.Assert.assertEquals(Assert.java:64)
    at junit.framework.Assert.assertEquals(Assert.java:195)
    at junit.framework.Assert.assertEquals(Assert.java:201)
    at com.bitdual.server.dao.ShardedCounterTest$3.run(ShardedCounterTest.java:77)

推荐答案

JUnit框架仅捕获运行测试的主线程中的断言错误。它不知道新的生成线程中的异常。
为了做到正确，你应该将线程的终止状态传递给主线程。你应该正确地同步线程，并使用某种共享变量来指示嵌套线程的结果。

The JUnit framework captures only assertion errors in the main thread running the test. It is not aware of exceptions from within new spawn threads. In order to do it right, you should communicate the thread's termination state to the main thread. You should synchronize the threads correctly, and use some kind of shared variable to indicate the nested thread's outcome.

编辑：

这是一个可以提供帮助的通用解决方案：

Here is a generic solution that can help:

class AsynchTester{
    private Thread thread;
    private AssertionError exc; 

    public AsynchTester(final Runnable runnable){
        thread = new Thread(new Runnable(){
            public void run(){
                try{            
                    runnable.run();
                }catch(AssertionError e){
                    exc = e;
                }
            }
        });
    }

    public void start(){
        thread.start();
    }

    public void test() throws InterruptedException{
        thread.join();
        if (exc != null)
            throw exc;
    }
}

你应该在构造函数中传递runnable，并且然后你只需要调用start（）来激活，test（）来调用。如果需要，测试方法将等待，并将在主线程的上下文中抛出断言错误。

You should pass it the runnable in the constructor, and then you simply call start() to activate, and test() to validate. The test method will wait if necessary, and will throw the assertion error in the main thread's context.

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