JUnit @Rule与@Before的生命周期交互

I have some JUnit tests that use the TemporaryFolder @Rule. They use the TemporaryFolder in a @Before method to perform some setup:

我有一些使用TemporaryFolder @Rule的JUnit测试。他们在@Before方法中使用TemporaryFolder来执行一些设置：

@Rule
public TemporaryFolder folder = new TemporaryFolder();

@Before
public void init() {
  folder.newFile("my-file.txt");
}

@Test
public void myTest() { ... }

Most of the time this works perfectly. However, when using the SpringJUnit4ClassRunner I find that in some cases the init() method is invoked before the Statement inside my TemporaryFolder instance is applied. Because of this, the temporary folder location is unset (i.e: null) when folder is used within init() and my file ends up in the working directory, not /tmp.

大部分时间这都很完美。但是，在使用SpringJUnit4ClassRunner时，我发现在某些情况下，在应用TemporaryFolder实例中的Statement之前调用init（）方法。因此，在init（）中使用文件夹时，临时文件夹位置未设置（即：null），而我的文件最终在工作目录中，而不是/ tmp。

So in some cases @Before methods are executed ahead of the rules, however, I can't establish a definite pattern. I occasionally see a similar problem with some of my own rule implementations.

所以在某些情况下@Before方法在规则之前执行，但是，我无法建立一个明确的模式。我偶尔会看到一些与我自己的规则实现类似的问题。

Is there any way that I can ensure that my rule statements are applied before any setup methods?

有什么方法可以确保在任何设置方法之前应用我的规则语句？

2 个解决方案

#1

In JUnit 4.10, BlockJUnit4ClassRunner (the superclass of SpringJUnit4ClassRunner) appears to take care to construct Statement chains in such a way that rules run before any @Before methods. From JUnit 4.10:

在JUnit 4.10中，BlockJUnit4ClassRunner（SpringJUnit4ClassRunner的超类）似乎注意构造Statement链，使得规则在任何@Before方法之前运行。从JUnit 4.10：

protected Statement methodBlock(FrameworkMethod method) {
    // ...
    Statement statement= methodInvoker(method, test);
    statement= possiblyExpectingExceptions(method, test, statement);
    statement= withPotentialTimeout(method, test, statement);
    statement= withBefores(method, test, statement);
    statement= withAfters(method, test, statement);
    statement= withRules(method, test, statement);
    return statement;
}

JUnit 4.7 appears to stitch Statement chains together in a different order:

JUnit 4.7似乎以不同的顺序将Statement链接在一起：

Statement statement= methodInvoker(method, test);
statement= possiblyExpectingExceptions(method, test, statement);
statement= withPotentialTimeout(method, test, statement);
statement= withRules(method, test, statement);
statement= withBefores(method, test, statement);
statement= withAfters(method, test, statement);
return statement;

spring-test-3.0.5's parent POM seems to indicate that it depends on JUnit 4.7. I wonder if getting it to use a newer JUnit would help?

spring-test-3.0.5的父POM似乎表明它依赖于JUnit 4.7。我想知道是否使用更新的JUnit会有所帮助吗？

#2

For what it's worth, I've used the following as a quick workaround:

对于它的价值，我使用以下作为快速解决方法：

@Rule
public TemporaryFolder tmpFolder = new TemporaryFolder() {
    @Override
    protected void before() throws Throwable {
        if (getRoot() == null) {
            super.before();
        }
    }

    @Override
    public File newFile(String fileName) throws IOException {
        try {
            before();
        }
        catch (Throwable t) {
            throw new RuntimeException(t.getMessage(), t);
        }

        return super.newFile(fileName);
    }

    @Override
    public File newFolder(String folderName) {
        try {
            before();
        }
        catch (Throwable t) {
            throw new RuntimeException(t.getMessage(), t);
        }

        return super.newFolder(folderName);
    }
};

This ensures that the TemporaryFolder is initialized properly, regardless of whether the @Before methods are run before or after the rules.

这可确保正确初始化TemporaryFolder，无论@Before方法是在规则之前还是之后运行。

#1