I'm using this, and so far it's working just fine:

https://github.com/awslabs/aws-sam-local

I'm only testing Lambda functions with it, and not really testing APIG + Lambda integrations or anything fancier.

I prep the local db, mock a Lambda event, write the mocked event to a JSON file, then use command line options to run the event against AWS SAM local, then get the response and compare it to the expected response.