MockFileSystem extensions

[Robert Dailey]

Would you find the below extension methods useful? If so, I am happy to open a pull request. I'm hesitant to do so right away because I'm not sure if these should be extension methods in this library or if I should contribute them as actual class members upstream (upstream being the actual IO.Abstractions package).

I found these extension methods to be absolutely invaluable in my own code base in conjunction with the Extensions package. It eliminates a lot of boilerplate in my unit tests, namely these:

var fs = new MockFileSystem();
var myDir = fs.CurrentDirectory().SubDirectory("dir");
var myFile = fs.CurrentDirectory().File("file.txt");

// Creating empty files
fs.AddFile(myFile.FullName, new MockFileData(""));
// Becomes
fs.AddEmptyFile(foo);

// Specifying `FullName` all over the place...
fs.AddDirectory(myDir.FullName);
// Becomes
fs.AddDirectory(myDir);

If you could provide some guidance and feedback, I'm happy to move this to a PR. Thanks for your time!

public static class MockFileSystemExtensions
{
    public static void AddEmptyFile(this MockFileSystem fs, string path)
    {
        fs.AddFile(path, new MockFileData(""));
    }

    public static void AddEmptyFile(this MockFileSystem fs, IFileInfo path)
    {
        fs.AddEmptyFile(path.FullName);
    }

    public static void AddDirectory(this MockFileSystem fs, IDirectoryInfo path)
    {
        fs.AddDirectory(path.FullName);
    }

    public static void AddFile(this MockFileSystem fs, IFileInfo path, MockFileData data)
    {
        fs.AddFile(path.FullName, data);
    }

    public static MockFileData GetFile(this MockFileSystem fs, IFileInfo path)
    {
        return fs.GetFile(path.FullName);
    }
}

[Luigi Grilli]

hi @rcdailey ,
The above looks usefull to me.
In my opinion, they should be part of the base package but I know @fgreinacher is not really into it.
@fgreinacher can you please review the above and see if it makes sense to add them to the TestableIO.System.IO.Abstractions.TestingHelpers library.

If not the only alternative is to create a second library in this repo, something like TestableIO.System.IO.Abstractions.TestingHelpers.Extensions, otherwise the normal extensions would depend on the testing library which doesn't make any sense.

[Florian Greinacher]

I'm also fine adding them to MockFileSystem. The changes go well with existing methods like AddFileFromEmbeddedResource. I just don't want to change the core abstractions like IFile or IDirectory.