I figured I would chime in. I've used LocalStack to "mock" AWS in CI for my two most-recent employers and worked without a hitch. Mocked DynamoDB, SQS, Kinesis and SNS without an issue. There was a single gotcha about the way that the FIFO queues needed to be named and it also didn't accept a default parameter for something relating SQS but other than that it was smooth sailing.
