Cloud integration testing for Lambdas

[ceilfors]

Integration testing is becoming very important in serverless architecture. This is because our architecture will consist of services that are only available in the cloud. The integration testing though is becoming quite tricky. If you have a Lambda triggered by an S3 change for example, how do you test if it is triggered by an S3 change?

One might argue that I should be using localstack. My experience in localstack is it doesn't give me the confidence of pushing my application to production, as there's no guarantee that it's going to be a "production-like" environment.

Discussion
Currently Laconia has a component for testing which can be found here. It's not documented in laconiajs.io as I'm not confident whether this is something helpful for the community. One thing that I wasn't confident about is the concept of "Remote spying" through S3.

What's everyone's thoughts on this topic? Is "Remote spying" something that the community would find helpful? One pain that I see is also the lack of integration with a deployment tools, which mean I would need developers to create their own S3 bucket before they can use the spy capability.

How else might we help developers on this area?