如何在类路径上模拟属性文件的存在? [英] How can I mock the presence of a properties file on the classpath?

问题描述

这肯定是一个常见问题.我有一个类似my-settings.properties的属性文件，该文件由应用程序类读取.当我编写测试类时，它需要测试my-settings.properties中可能出现的各种情况，以确保最大的代码覆盖率(例如，空属性文件，基本属性文件等).但是我的src/test/resources中只能有一个my-settings.properties.

This surely is a common problem. I have a properties file like my-settings.properties which is read by an application class. When I write a test class, it needs to test different scenarios of things that could be present in my-settings.properties in order to ensure maximum code coverage (e.g. empty properties file, basic properties file etc). But I can only have one my-settings.properties in my src/test/resources.

如果只有一些注释，那将是非常好的

What would be really great is if there was just some annotation

@MockFileOnClassPath(use = "my-settings-basic.properties", insteadOf = "my-settings.properties")

然后，我可以在我的/src/test/resources中仅包含多个my-settings-XXX.properties文件，并在每种测试方法上标注正确的文件.但是我找不到这样的东西.我正在使用JUnit 4.12.

Then I could just have multiple my-settings-XXX.properties files in my /src/test/resources and just annotated the correct one on each test method. But I can't find anything like this. I'm using JUnit 4.12.

我可以想到几个粗略的解决方案:

I can think of a couple of crude solutions:

1. 在每次测试之前，请在文件系统上找到文件，使用文件系统I/O复制该文件，然后在测试后再次将其删除.但这很笨拙，并且涉及很多冗余.更不用说我什至不确定classpath目录是否可写.
2. 使用模拟框架模拟getResource.我什至不知道该怎么办，特别是因为有上百万种不同的方式来获取文件(this.getClass().getResourceAsStream(...)，MyClass.class.getResourceAsStream(...)，ClassLoader.getSystemClassLoader().getResourceAsStream(...)等)

1. Before each test, find the file on the file system, copy it using filesystem I/O, then delete it again after the test. But this is clumsy and involves a lot of redundancy. Not to mention I'm not even sure whether the classpath directory will be writable.
2. Use a mocking framework to mock getResource. No idea how I would even do that, especially as there are a million different ways to get the file (this.getClass().getResourceAsStream(...), MyClass.class.getResourceAsStream(...), ClassLoader.getSystemClassLoader().getResourceAsStream(...) etc.)

我只是认为这肯定是一个普遍的问题，也许在JUnit，Mockito，PowerMock，EasyMock或类似的东西中已经有解决方案了?

I just think this must be a common problem and maybe there is already a solution in JUnit, Mockito, PowerMock, EasyMock or something like that?

编辑:有人指定此问题与

EDIT: Someone has specified that this question is a duplicate of Specifying a custom log4j.properties file for all of JUnit tests run from Eclipse but it isn't. That question is about wanting to have a different properties file between the main and test invocations. For me I want to have a different properties file between a test invocation and another test invocation.

推荐答案

我发现，每当处理文件时，最好引入Resource的概念.

I find that whenever dealing with files, it's best to introduce the concept of a Resource.

例如:

public interface Resource {
    String getName();
    InputStream getStream();
}

然后您可以通过依赖项注入来传递资源:

Then you can pass the resource in via dependency injection:

public class MyService {
    private final Properties properties;

    public class MyService(Resource propFile) {
        this.properties = new Properties();
        this.properties.load(propFile.getStream());
    }

    ...
}

然后，在生产代码中，可以使用ClasspathResource或FileResource或URLResource等，但是在测试中，可以使用StringResource等.

Then, in your production code you can use a ClasspathResource or maybe a FileResource or URLResource etc but in your tests you could have a StringResource etc.

请注意，如果您使用spring，那么您已经对这个概念有所了解.更多详细信息此处

Note, if you use spring you already have an implenentation of this concept. More details here

这篇关于如何在类路径上模拟属性文件的存在?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！