Testing
Serverless integration testing is harder than testing a monolith. Functions are isolated by design, services communicate through events and queues, and the infrastructure is someone else's computer. The same properties that make serverless scalable and cheap also make it annoying to test. This guide covers the strategies that
Testing
Unit tests with mocked AWS SDK calls tell you that your function logic is correct. They don't tell you whether your DynamoDB queries actually work, whether your S3 key paths are right, or whether your SQS message format triggers the right Lambda. LocalStack fills that gap: it runs
Serverless
The Serverless Framework has become the de facto standard for deploying multi-cloud serverless applications. But most teams using it focus on deployment and skip the testing layer — or end up with a fragile test setup that requires a live AWS environment to run. A well-structured Serverless Framework project
Testing
Integration tests against real AWS catch issues that mocks and local emulators miss: IAM permission errors, DynamoDB capacity limits, API Gateway timeout mismatches, and cold start behavior. Deploy a dedicated test stack, make real HTTP calls, assert on real responses, and clean up test data in teardown. Control costs with
Testing
AWS CDK has two testing approaches that serve different purposes and are commonly confused: 1. Fine-grained assertions (hasResourceProperties, hasResource, resourceCountIs) — assert specific properties of specific resources 2. Snapshot tests (toMatchSnapshot) — assert the entire synthesized CloudFormation template hasn't changed Most CDK projects use one or the other exclusively,
Testing
AWS SQS and SNS are foundational to event-driven architectures on AWS.
Testing
AWS SQS and SNS are everywhere in serverless and microservice architectures. They're also surprisingly easy to test badly.
AWS
AWS SAM (Serverless Application Model) gives you infrastructure-as-code for serverless applications, but testing SAM applications before deployment has historically been painful. The sam local toolchain has matured significantly — this guide covers how to use it effectively for unit tests, local integration tests, and pre-deploy validation. Why SAM
Testing
AWS SAM CLI lets you invoke Lambda handlers locally with sam local invoke and spin up a local API Gateway with sam local start-api. Use it for fast feedback on handler logic and event parsing before deploying to AWS. Combine with environment variable overrides and Docker for CI integration.
Testing
AWS Glue ETL jobs are PySpark scripts that run in AWS-managed Spark clusters.
AWS
AWS EKS adds a Kubernetes control plane on top of AWS infrastructure, which means you're testing both Kubernetes abstractions and AWS-specific behavior.
AWS
Testing containerized workloads on AWS ECS and Fargate requires a different mindset than testing traditional server-based applications.