Europe 2026
Beyond Code Coverage: Functionality Testing with Playwright MCP — Marlene Mhangami, Microsoft
Overview
This talk explores how to move beyond traditional code coverage metrics to ensure true functionality testing, especially in the context of AI-assisted development. It argues that while AI can increase code output, its true productivity gains are amplified by clean codebases and robust testing. The presentation introduces Playwright as a tool for end-to-end browser testing, demonstrating how it can be integrated with AI agents to accelerate development workflows, particularly within a test-driven development (TDD) framework.
Who should watch
- AI engineers and developers using AI for coding assistance.
- Product Managers and builders evaluating the effectiveness of AI in development.
- Teams struggling with code quality and entropy amplified by AI.
- Engineers looking to implement more effective testing strategies beyond unit tests.
- Developers interested in integrating AI agents with testing frameworks.
Key takeaways
- AI can increase code volume, but its impact on productivity depends heavily on how it's used and the quality of the codebase.
- Clean codebases, including good test coverage, type coverage, and modularity, amplify AI's productivity benefits.
- Over-reliance on unit tests or AI-generated tests that don't validate system behavior can lead to false positives and increased rework.
- Playwright is an open-source framework for automating end-to-end browser testing, simulating user interactions.
- Integrating Playwright with AI agents can speed up the TDD cycle by quickly generating failing tests and then code to pass them.
- The refactoring stage is crucial, where developers should spend the most time improving code generated by AI.
- Playwright MCP (Multi-Channel Protocol) and Playwright agents offer ways to connect coding agents for planning, generating, and fixing tests.
- Focusing on feature-based behavior testing, rather than implementation details, leads to more resilient tests.
Notable quotes
*Clean code bases amplify AI gains and AI productivity, while unchecked AI in a code base is going to amplify entropy.*
*The value that we are wanting to see as developers from AI relies or hinges on us having a clean code base.*
Unofficial community note. Prefer the recording for nuance.