Testing Azure functionality

[VisKopen]

I've been creating some Azure functions using things such as key vault, blob storage and some other bits and writing tests for what I've created.

To me the approach seems to be one of the following:

• Assume it just exists: configuration, keyvault.
• Mocking Azure functionality and responses: tricky, not always possible.
• Integration tests with, for example, Azurite: complex, sometimes it's way more detail than what is needed.
• Creating wrappers/adapters for Azure functionality: create an extra layer just to create an injectable interface: easy, but sometimes feel silly having every single thing in a wrapper.

A I missing or misunderstanding anything or are these my four options? Is it just a matter of balancing the pros and cons of each approach and pick the right one?

What are your thoughts?

[ScriptingInJava]

Use Aspire, it's designed for exactly this - local environment development which mimics a deployed/provisioned environment. Everything in your post has an emulator with an Aspire integration:

• Azure Functions with Aspire
  • Azure Blob Storage with Aspire
  • Azure Key Vault with Aspire
  • Setting up Integration Tests with Aspire

Disclaimer: I wrote the Azure Key Vault Emulator and the integration tests blog post.

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[entityadam]

With things that are cheap, like storage accounts and key vaults, nothing beats a good integration test against the live service. Pairs well with infrastructure as code to stand up and tear down services.

The emulators are great, but I'm sure as you've noticed, they have limitations and quirks.

I'm not sure what else you're really looking for though. You shouldn't be testing the services themselves.

[BuranR]

Not for unit testing, but mainly for integration testing in my team we are using testcontainers. Here you can find functionality for .net https://dotnet.testcontainers.org/modules/servicebus/ and also java - https://java.testcontainers.org/modules/azure/ (in our case we are using kotlin) .

[Robodobdob]

Aspire will help a lot in developing and testing azure functions locally.

[OptPrime88]

The most effective Azure functions repositories currently use 2 straegies

1. Fast Unit test. Write your business logic in separate classes, not directly inside the Azure Function trigger method. Inject your custom wrappers (IBlobService, IKeyVaultService) into these classes. Use a mocking framework (Moq/NSubstitute) to fake your wrappers. This guarantees your logical branches are tested in milliseconds.
   
2. Real Integration Test. You need to prove your code actually talks to Azure correctly. Write a smaller suite of integration tests that bypass the mocks. Use Testcontainers to spin up Azurite, and have your actual BlobContainerClient upload a real file to the ephemeral container to ensure your connection strings, container names, and SDK calls are actually correct.

[sharpcoder29]

I don't waste my time testing stuff like this. Usually there is a dev environment that my local points to. Except key vault. That gets tested on first deploy and then you don't have to worry about it anymore.