单元测试文件 I/O

问题描述：

阅读 Stack Overflow 上现有的与单元测试相关的线程，我找不到关于如何对文件 I/O 操作进行单元测试的明确答案.我最近才开始研究单元测试，之前已经意识到它的优点，但很难习惯先编写测试.我已将我的项目设置为使用 NUnit 和 Rhino Mocks，虽然我了解它们背后的概念，但我在理解如何使用 Mock 对象时遇到了一些麻烦.

Reading through the existing unit testing related threads here on Stack Overflow, I couldn't find one with a clear answer about how to unit test file I/O operations. I have only recently started looking into unit testing, having been previously aware of the advantages but having difficulty getting used to writing tests first. I have set up my project to use NUnit and Rhino Mocks and although I understand the concept behind them, I'm having a little trouble understanding how to use Mock Objects.

具体来说，我有两个问题想要回答.首先，单元测试文件 I/O 操作的正确方法是什么?其次，在我尝试学习单元测试的过程中，我遇到了依赖注入.在设置并运行 Ninject 之后，我想知道我是否应该在单元测试中使用 DI，或者直接实例化对象.

Specifically I have two questions that I would like answered. First, what is the proper way to unit test file I/O operations? Second, in my attempts to learn about unit testing, I have come across dependency injection. After getting Ninject set up and working, I was wondering whether I should use DI within my unit tests, or just instantiate objects directly.

答

查看 TDD 教程使用 Rhino Mocks 和 SystemWrapper.

Check out Tutorial to TDD using Rhino Mocks and SystemWrapper.

SystemWrapper 包装了许多 System.IO 类，包括 File、FileInfo、Directory、DirectoryInfo 等.您可以查看完整列表.

SystemWrapper wraps many of System.IO classes including File, FileInfo, Directory, DirectoryInfo, ... . You can see the complete list.

在本教程中，我将展示如何使用 MbUnit 进行测试，但它与 NUnit 完全相同.

In this tutorial I'm showing how to do testing with MbUnit but it's exactly the same for NUnit.

您的测试将如下所示:

[Test]
public void When_try_to_create_directory_that_already_exists_return_false()
{
    var directoryInfoStub = MockRepository.GenerateStub<IDirectoryInfoWrap>();
    directoryInfoStub.Stub(x => x.Exists).Return(true);
    Assert.AreEqual(false, new DirectoryInfoSample().TryToCreateDirectory(directoryInfoStub));

    directoryInfoStub.AssertWasNotCalled(x => x.Create());
}

单元测试文件 I/O

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