如何对这个C#扩展方法进行单元测试？

Question

我只是不确定如何模拟情况来测试这个.我应该在文件系统上实际创建文件吗？

public static void DeleteIfExists(this FileInfo fileInfo)
{
   if (fileInfo.Exists)
   {
      fileInfo.Delete();
   }
}

Answer 1

我会使用像RhinoMocks这样的模拟框架.

[Test]
public void ShouldDeleteAFileWhenItExists()
{
    var mockInfo = MockRepository.GenerateMock<FileInfo>();
    mockInfo.Expect( i => i.Exists ).Return( true ).Repeat.Once();
    mockInfo.Expect( i => i.Delete() ).Repeat.Once();

    var extensions = new FileInfoExtensions();

    extensions.DeleteIfExists( mockInfo );

    mockInfo.VerifyAllExpectations();
}

[Test]
public void ShouldNotDeleteAFileWhenItDoesNotExist()
{
    var mockInfo = MockRepository.GenerateMock<FileInfo>();
    mockInfo.Expect( i => i.Exists ).Return( false ).Repeat.Once();
    mockInfo.Expect( i => i.Delete() ).Repeat.Never();

    var extensions = new FileInfoExtensions();

    extensions.DeleteIfExists( mockInfo );

    mockInfo.VerifyAllExpectations();
}

Delete时抛出异常等的其他测试