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File system abstractions for building testable applications.
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File system abstractions for building testable applications.

Writing code that interacts with files can be a pain. Testing this code can be even more of a pain.

Enable.Extensions.FileSystem provides a flexible set of file system abstractions that allow you to write the same code for working with files regardless of whether you are interacting with files on your local machine or files stored in a cloud offering such as Azure Storage.

Best of all, these abstractions allow you to easily mock file system access during tests, making your unit tests run faster and more predictably.

Enable.Extensions.FileSystem currently provides two file system implementations:

In addition to these packages, an additional Enable.Extensions.FileSystem.Abstractions package is available. This contains the basic abstractions that the implementations listed above build upon. Use Enable.Extensions.FileSystem.Abstractions to implement your own file system provider.

Package name NuGet version
Enable.Extensions.FileSystem.Abstractions NuGet
Enable.Extensions.FileSystem.AzureStorage NuGet
Enable.Extensions.FileSystem.Physical NuGet


The following example demonstrates creating, reading and deleting a file.

using System;
using System.Threading.Tasks;
using Enable.Extensions.FileSystem.Physical;

namespace FileSystemSamples
    public class Program
        public static void Main() => MainAsync().GetAwaiter().GetResult();

        public static async Task MainAsync()
            // We start by declaring the absolute path to the directory we
            // want to work with.
            var directory = @"C:\some\absolute\path";
            // We then construct a representation of the physical file system
            // under this directory. Note that the files we want to work must
            // be rooted under `directory`. If we try walking out of this
            // directory then we'll be hit with an exception.
            using (var fileSystem = new FileSystem(directory))
                // Let's start with some content that we want to write to disk.
                var content = "Hello, World!";

                // Files are identified by relative paths, with paths relative
                // to `directory`, which we specified above. Here we declare
                // the file we want to work with.
                var filePath = @"relative\path\to\file.txt";

                // We then save this text to this file.
                await fileSystem.SaveFileAsync(filePath, content);

                // Let's now check that this file now exists.
                var fileInfo = await fileSystem.GetFileInfoAsync(filePath);

                // The following will print `True`.

                // Now let's try and read the contents of this file.
                using (var stream = await _sut.GetFileStreamAsync(filePath))
                using (var reader = new StreamReader(stream, Encoding.UTF8))
                    // Here `text` will be the string `"Hello, World!"`.
                    var text = reader.ReadToEnd();

                // Finally, let's be good citizens and clean up after ourselves
                // by deleting the file we just created. If we don't do this,
                // the file will live on forever, long after we dispose of our
                // `fileSystem`.
                await fileSystem.DeleteFileAsync(filePath);

Here we're using the physical file system implementation to interact with our files. However, how we work with files is the same across any of the file system implementations. The only differences are in how you initially construct the file system provider.

For example, to work with files stored in an Azure Storage account, all we need to do is:

  1. Bring in the namespace Enable.Extensions.FileSystem.AzureStorage;

  2. Change the line:

    using (var fileSystem = new FileSystem(directory))


    using (var fileSystem = new AzureBlobStorage("account-name", "account-key", "container-name"))

The rest of the sample remains unchanged!

Here account-name is the name of your own Azure Storage account and account-key the key to use to access the account. The steps you need to take to obtain this from the Azure Portal can be found in the article Configure Azure Storage connection strings. Here we're using Azure Blob Storage, so we need to specify a container name, which we do as the third parameter to the AzureBlobStorage constructor.

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