# [QA.FT.2] Validate system interactions and data flows with integration tests
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 **Category:** FOUNDATIONAL 

 Integration tests evaluate the interactions between multiple components that make up the system, including infrastructure and external systems. The goal of integration testing is to help ensure that these interactions and data flows work together, ensuring that recent changes have not disrupted any interfaces or introduced undesired behaviors. 

 Integration tests often run much slower than unit testing due to the fact that they interact with real system, such as databases, message queues, and external APIs. Strive to make integration tests as efficient as possible by optimizing setup and tear down using automation and infrastructure as code (IaC). Optimize test execution by running tests in parallel where possible. This allows for quicker feedback loops and makes it possible to run integration tests through continuous integration pipelines. 

 While integration tests should involve real components, they should still be isolated from production or shared environments where possible. This helps ensure that tests do not inadvertently affect real data or services. Consider using dedicated emulation, containers, or cloud-based test environments to make tests more efficient, consistent, and safe. 

 Just as with unit tests, adopting [Test-Driven Development (TDD)](https://www.agilealliance.org/glossary/tdd/) by writing tests before the software is developed helps to highlight potential integration pain points early, and verifies that the interfaces between components are correctly implemented from the start. 

**Related information:**
+  [AWS Well-Architected Reliability Pillar: REL12-BP03 Test functional requirements](https://docs.aws.amazon.com/wellarchitected/latest/reliability-pillar/rel_testing_resiliency_test_functional.html) 
+  [AWS Deployment Pipeline Reference Architecture](https://aws-samples.github.io/aws-deployment-pipeline-reference-architecture/application-pipeline/index.html) 
+  [Getting started with testing serverless applications](https://aws.amazon.com/blogs/compute/getting-started-with-testing-serverless-applications/) 
+  [Amazon's approach to high-availability deployment: Integration testing](https://youtu.be/bCgD2bX1LI4?t=1480) 
+  [Building hexagonal architectures on AWS - Write and run tests from the beginning](https://docs.aws.amazon.com/prescriptive-guidance/latest/hexagonal-architectures/best-practices.html)