在JUnit测试中处理System.exit（0） [英] Dealing with System.exit(0) in JUnit tests

问题描述

我正在为现有的Java Swing应用程序实现一些测试，这样我就可以安全地重构和扩展代码而不会破坏任何东西。我开始在JUnit中进行一些单元测试，因为这似乎是最简单的入门方式，但现在我的首要任务是创建一些端到端的测试以整体运行应用程序。

I am implementing some tests for an existing Java Swing application, so that I can safely refactor and extend the code without breaking anything. I started with some unit tests in JUnit, since that seems the simplest way to get started, but now my priority is to create some end-to-end tests to exercise the application as a whole.

我在每个测试中重新启动应用程序，将每个测试方法放在一个单独的测试用例中，并在Ant中使用 fork =yes选项 junit 任务。但是，我想要作为测试实现的一些用例涉及用户退出应用程序，这导致调用System.exit（0）的方法之一。这被JUnit视为错误： junit.framework.AssertionFailedError：分叉的Java VM异常退出。

I am starting the application afresh in each test by putting each test method in a separate test case, and using the fork="yes" option in Ant's junit task. However, some of the use cases I would like to implement as tests involve the user exiting the application, which results in one of the methods calling System.exit(0). This is regarded by JUnit as an error: junit.framework.AssertionFailedError: Forked Java VM exited abnormally.

是有一种方法告诉JUnit退出代码为零实际上是否正常？

Is there a way to tell JUnit that exiting with a return code of zero is actually OK?

推荐答案

我如何处理这是安装一个安全管理器，在调用System.exit时抛出异常。然后有代码捕获异常并且不会使测试失败。

How I deal with that is to install a security manager that throws an exception when System.exit is called. Then there is code that catches the exception and doesn't fail the test.

public class NoExitSecurityManager
    extends java.rmi.RMISecurityManager
{
    private final SecurityManager parent;

    public NoExitSecurityManager(final SecurityManager manager)
    {
        parent = manager;
    }

    public void checkExit(int status)
    {
        throw new AttemptToExitException(status);
    }

    public void checkPermission(Permission perm)
    {
    }
}

然后在代码中，类似于：

And then in the code, something like:

catch(final Throwable ex)
{
    final Throwable cause;

    if(ex.getCause() == null)
    {
        cause = ex;
    }
    else
    {
        cause = ex.getCause();
    }

    if(cause instanceof AttemptToExitException)
    {
        status = ((AttemptToExitException)cause).getStatus();
    }
    else
    {
        throw cause;
    }
}

assertEquals("System.exit must be called with the value of " + expectedStatus, expectedStatus, status);

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