Testing CloudTable dependent code using the Azure Storage Emulator and NUnit

TestingCloudTableWithAzureStorageEmulator.cs

public class TestingCloudTableWithAzureStorageEmulator
{
  private CloudTableClient developmentCloudTableClient;
  private CloudTable emulatedCloudTable;
  
  [OneTimeSetUp]
  public void OneTimeSetUp()
  {
      var azureStorageEmulatorProcess = Process.Start("C:\\Program Files (x86)\\Microsoft SDKs\\Azure\\Storage Emulator\\AzureStorageEmulator.exe", "start");
      azureStorageEmulatorProcess?.WaitForExit(2000);
      this.developmentCloudTableClient = CloudStorageAccount.DevelopmentStorageAccount.CreateCloudTableClient();
  }

  [OneTimeTearDown]
  public void OneTimeTearDown()
  {
      var azureStorageEmulatorProcess = Process.Start("C:\\Program Files (x86)\\Microsoft SDKs\\Azure\\Storage Emulator\\AzureStorageEmulator.exe", "stop");
      azureStorageEmulatorProcess?.WaitForExit(2000);
  }
  
  [SetUp]
  public void SetUp()
  {
      this.emulatedCloudTable = this.developmentCloudTableClient.GetTableReference("unittests");
      if (this.emulatedCloudTable.Exists())
      {
          this.emulatedCloudTable.Delete();
      }
      this.emulatedCloudTable.Create();
  }

  [TearDown]
  public void TearDown()
  {
      this.emulatedCloudTable.Delete();
  }
}

Very interesting discussion and something I've been thinking about how best to test an Azure function with a table binding. I had thought about an approach similar to what's in this gist relying on Azure Storage Emulator but I felt it's not isolated and repeatable enough. Fortunately CloudTableClient exposes a DelegatingHandler property which you can assign a stub handler to providing the JSON response that would come back from the storage account.

Here is an example of how it works https://gist.github.com/vivianroberts/4bf161fdd6a9692d202888130e84df6b

To get the structure of the responses I use Azure Cli with the AZURE_STORAGE_CONNECTION_STRING environment variable set to "UseDevelopmentStorage=true" and then set up a proxy in Postman on 10002 to capture the requests. Next I switch off the proxy and start Azure Storage Emulator and fire the captured requests from Postman to get the response body.

Hopefully this approach provides a good balance between all the suggestions in this discussion 😊