End-to-End Testing at the PR Stage

LY Corporation has continuously improved its End-to-End (E2E) testing process to reduce the risk of service outages. The E2E testing tool, which has higher fidelity than existing unit tests or integration tests, connects to the messaging server in the same way as the actual LINE app to verify system behavior.

Recently, the company implemented a feature that allows developers to run tests on individual branches when creating a PR (Pull Request). This aims to detect issues early, shorten development iteration cycles, and increase test coverage.

To make this project successful, a container-based isolated test environment was built through collaboration across multiple teams. In particular, the focus was on building a fully isolated environment to prevent data contamination issues that can occur when using shared storage.

• HBase in a box: A container that makes it easy to build an isolated storage environment.
• Redis & Kafka: Support for a Kubernetes-based local test cluster and containerized deployment.
• Beta container: Utilizes an environment that deploys PR branches as containers on a shared Kubernetes cluster.

During implementation, more time was spent resolving complex edge cases than on simple feature development. Key tasks included migrating to Scala 3.3 LTS and aligning library dependencies, as well as implementing sophisticated Health Check logic to ensure the stable startup of services with long boot times, such as HBase.