Test First Development: Defining Success Criteria to Drive Quality and Collaboration

Test First is a modern engineering practice that anchors the delivery of working software in clarity, confidence, and quality. It is a shift-left strategy where tests are defined before implementation begins, guiding design and enabling faster feedback loops.

At its core, Test First, as a practice, promotes defining success criteria upfront—whether through examples, scenarios, specifications, or executable tests. This clarity ensures that teams understand what “good” looks like before they write any code or build any components.

Dual Support: Manual and Automated

Test First applies to both manual and automated validation:

• Manual Test First practices include defining acceptance criteria, visual specifications, and test cases before development. This enables effective collaboration between developers, testers, designers, and product owners.
• Automated Test First (such as TDD or ATDD) takes it further by encoding those criteria in executable tests—written before the implementation. These tests drive design, expose ambiguity, and provide a safety net for change.

While manual testing has its place in exploratory and usability validation, automation is preferred. It enables fast feedback, supports continuous integration, and reduces the risk of regressions. In mature teams, manual Test First practices are often transitional scaffolding toward full automation.

Test First is Not Just a Testing Practice

Test First is a design practice, a collaboration practice, and a feedback practice. It improves flow by reducing rework, aligning expectations early, and ensuring that development efforts are always grounded in real customer outcomes.

In teams using Test First well, tests are not written to prove code works—they’re written to define what “working” means.