I developed on Lambda with SAM and testing was pretty dang quick. IMO, Lambda works great for light weight event processing. I don’t know your use case. I wrote some Java based Lambdas, and despite not being a huge Java fan, the Lambda experience was fairly easy for me. I was essentially processing events coming in from an SQS queue, performing some enrichment, and dropping things in other queues for downstream services to consume. Are you sure Lambda is the right solution for your problem?