Ability to lock a MockFile for testing

[gregmcguffey]

It would be really helpful to mark a MockFile as being locked, so locked file logic can easily be tested. This would related to commands like File.Delete, File.WriteAll*, ect. Or is this possible now?

[tathamoddie]

This isn't currently implemented in the testing helpers.

The fake file system doesn't track if files have been opened exclusively or not:

https://github.com/System-IO-Abstractions/System.IO.Abstractions/blob/master/System.IO.Abstractions.TestingHelpers/MockFile.cs#L361

Sounds like an interesting pull request though if you care to start coding something up! 😄

[erenes]

Hi guys, one of my customers reported an issue with file locking, so I am implementing it in my forked repo. Currently my approach is to add a FileShare property to the Mockfile that is checked when opening a stream or using one of the File methods.

I considered implementing it with a whole dictionary of streams that are using different FileAccess/FileShare parameters, but for my scenario that seems like a lot of wasted effort.

To illustrate, this is one of the tests:

    [Test]
    public void MockFile_Lock_FileShareNoneThrowsOnOpenRead()
    {
        string filepath = XFS.Path(@"c:\something\does\exist.txt");
        var filesystem = new MockFileSystem(new Dictionary<string, MockFileData>
        {
            { filepath, new MockFileData("I'm here") { CurrentFileShare = FileShare.None }}
        });

        Assert.Throws(typeof(IOException), () => filesystem.File.OpenRead(filepath));
    }

I am not entirely satisfied about the name "CurrentFileShare". Compared to writing a full File System simulation, I do think this way of marking locked files is easier to implement both in System.IO.Abstractions, as well as when writing unit tests.

Any feedback / thoughts is welcome :)

[fgreinacher]

This is released with https://github.com/System-IO-Abstractions/System.IO.Abstractions/releases/tag/v3.1.1