[Introduction to contract testing - Part 1] The problem with end-to-end integrated tests

Summary

This introductory tutorial explains how end-to-end integration testing is used in distributed systems and why it becomes difficult to maintain as systems grow.

How It Works

Teams deploy system components into a shared environment designed to resemble production. Tests send requests through the full path—such as the interface, gateways, and multiple microservices—and check whether the expected outcome occurs. Passing tests can provide confidence that the components work together.

Main Drawbacks

These tests are slow because requests pass through real systems and may trigger real application actions. They are often run sequentially, so test suites that take tens of minutes or longer are common.

Fragility and Troubleshooting

Failures can result from incorrect test data, software versions, test definitions, or environment configuration. Diagnosing them may require tracing requests through logs and observability tools, using correlation IDs, and identifying the failing application version.

Operational Burden

Teams must maintain test data and shared environments, coordinate which components are deployed, and decide whether a release is safe. End-to-end testing also cannot provide straightforward, complete coverage.

Release Bottleneck

Because components are tested together, teams may need to release them together. This creates dependencies and queues between teams and can make rollbacks more difficult.

Scaling Problem

As the number of teams and applications grows, costs can increase nonlinearly. The video cites rising environment complexity, latency, and quantity, along with longer builds, greater change risk, more developer downtime, and larger queues.

Guide and Tutorial Content

This is a conceptual introduction to end-to-end integration testing, its place in the CI/CD pipeline, and its scaling limitations. The subtitles include no product review or hands-on tutorial.

Main Speaker and Source

An unnamed presenter in a PactFlow video.