Posted on Jun 10, 2022

C#: Unit Testing Azure Files SDK

Azure Files is great service to store files like local disk. I use C# SDK to access to the service, but unit testing was not straight forward.

Sample code

Let's imagine we have C# code as below, which returns all share names from the Azure Files. I use DI for ShareServiceClient here. The code is quite simple, eh?

using Azure.Storage.Files.Shares; using Azure.Storage.Files.Shares.Models; namespace AzureFilesSample; public class AzureFileSampleService { private readonly ShareServiceClient shareServiceClient; public AzureFileSampleService(ShareServiceClient shareServiceClient) { this.shareServiceClient = shareServiceClient; } public async Task<List<string>> GetFileSharesAsync() { List<string> fileShares = new List<string>(); await foreach (ShareItem item in shareServiceClient .GetSharesAsync() .WithCancellation(CancellationToken.None)) { fileShares.Add(item.Name); } return fileShares; } }

Unit test

To write unit test for the above code, we need to mock ShareServiceClient. However, I cannot instantiate ShareItem as it only has internal constructor. After I browse its source code in github, I found ShareModelFactory class which let us instantiate related models.

This is the unit testing code. I use xUnit and moq library.

Use ShareModelFactory to instantiate items
Refer to Azure Mocking page to mock Azure response related object.

[Fact] public async Task Test1() { Mock<ShareServiceClient> mockedShareServiceClient = new Mock<ShareServiceClient>(); ShareItem shareItem1 = ShareModelFactory.ShareItem("name1", ShareModelFactory.ShareProperties()); ShareItem shareItem2 = ShareModelFactory.ShareItem("name2", ShareModelFactory.ShareProperties()); ShareItem[] pageValues = new[] { shareItem1, shareItem2 }; Page<ShareItem> page = Page<ShareItem>.FromValues(pageValues, default, new Mock<Response>().Object); Pageable<ShareItem> pageable = Pageable<ShareItem>.FromPages(new[] { page }); AsyncPageable<ShareItem> asyncPageable = AsyncPageable<ShareItem>.FromPages(new[] { page }); mockedShareServiceClient.Setup(x => x.GetSharesAsync(ShareTraits.None, ShareStates.None, null, CancellationToken.None)) .Returns(asyncPageable); AzureFileSampleService service = new AzureFileSampleService(mockedShareServiceClient.Object); var results = await service.GetFileSharesAsync(); Assert.Equal("name1", results.First()); Assert.Equal("name2", results.Last()); }