# The test suite as a regression sensor

DevFeed: [The test suite as a regression sensor](<https://devfeed.tech/articles/the-test-suite-as-a-regression-sensor-4425.md>)

Original publisher: [Read original article](<https://martinfowler.com/articles/sensors-for-coding-agents.html>)

Author: Martin Fowler (martin@martinfowler.com)

Published: 2026-05-27T15:01:00Z

Content type: article

Language: en

Sources: [Martin Fowler](<https://devfeed.tech/sources/martin-fowler.md>)

Topics: [AI-assisted coding](<https://devfeed.tech/topics/ai-assisted-coding.md>), [coding](<https://devfeed.tech/topics/coding.md>), [Code quality](<https://devfeed.tech/topics/code-quality.md>), [React](<https://devfeed.tech/topics/react.md>), [TypeScript](<https://devfeed.tech/topics/typescript.md>), [Front end](<https://devfeed.tech/topics/frontend.md>), [Back end](<https://devfeed.tech/topics/backend.md>), [mutation-testing](<https://devfeed.tech/topics/mutation-testing.md>), [Web](<https://devfeed.tech/topics/web.md>), [dashboards](<https://devfeed.tech/topics/dashboards.md>), [data](<https://devfeed.tech/topics/data.md>)

Tags: [agents](<https://devfeed.tech/tags/agents.md>), [ai](<https://devfeed.tech/tags/ai.md>), [apis](<https://devfeed.tech/tags/apis.md>), [backend](<https://devfeed.tech/tags/backend.md>), [code](<https://devfeed.tech/tags/code.md>), [code-quality](<https://devfeed.tech/tags/code-quality.md>), [coding-agents](<https://devfeed.tech/tags/coding-agents.md>), [data](<https://devfeed.tech/tags/data.md>), [frontend](<https://devfeed.tech/tags/frontend.md>), [react](<https://devfeed.tech/tags/react.md>), [sensor](<https://devfeed.tech/tags/sensor.md>), [skip-home-page](<https://devfeed.tech/tags/skip-home-page.md>), [testing](<https://devfeed.tech/tags/testing.md>), [typescript](<https://devfeed.tech/tags/typescript.md>), [web](<https://devfeed.tech/tags/web.md>)

## AI overview

This article examines how maintainability sensors can help coding agents and developers detect declining internal code quality and support self-correction. It discusses functional correctness, architectural fitness, maintainability, codebase structure, and the use of test suites as regression sensors, including mutation testing. The examples use an internal analytics dashboard built with TypeScript, NextJS, and React, with a backend that combines data from external APIs.

## Source excerpt

Birgitta Böckeler finishes her post on sensors for coding agents by examining the role of a test suite as a regression sensor, focusing on the role mutation testing can play. more...