admin@tnexa.org

TNExa / BDDtoTDD

From a raw idea to the tests that define it.

TNExa is building BDDtoTDD: a Claude-powered pipeline that turns a product idea into a behaviour specification, a domain model and the acceptance tests an AI coding agent such as Claude Code can then implement test-first.

In design · building with Claude

The problem

AI coding agents write code fast, but they build what they are told. When the idea behind the request is vague, the agent fills the gaps with guesses: rules go missing, scenarios are never written, and tests arrive after the code instead of before it.

A founder working alone has nobody to push back on a half-formed idea. BDDtoTDD plays that role: it asks the questions a good product team would ask, before a single line of code exists.

How it works

The pipeline runs in nine steps. Claude does the work of each step; the founder makes one decision and the result becomes the next step's input.

  1. Clarify intentClaude interviews the raw idea and proposes candidate goals. You pick one.
  2. Impact mapWho can help or block the goal, and how their behaviour must change.
  3. Choose sliceThe deliverable cut into user stories, sliced by user value.
  4. Example mappingRules, concrete examples and open questions for one story.
  5. FormulationThe story written out as a BDD narrative and scenarios.
  6. Use caseThe primary course and every failure path.
  7. Model and contractModel fields, payload contract and error types.
  8. Component boundariesDomain, API, presentation and composition, separated.
  9. Test structureTest classes, test names, test doubles and helpers: where TDD starts.

It stops at design. The output is a specification and a test structure, ready for Claude Code or a developer to implement test-first.

See a sample run of the first step →

Principles

Every question has a source

Each question the tool asks is traced to a published method — impact mapping, story mapping, specification by example, use cases, domain-driven design.

Improves ideas, never rejects them

The pipeline sharpens an idea. It is not a gatekeeper.

Tests before code

Acceptance tests are the hand-off, so the implementation is checked against what was agreed.

Where we are

TNExa is a one-person startup, founded in 2026 and not yet incorporated. We first built a native macOS app that drives Claude Code headlessly, from idea intake to spec authoring. Building it showed us that AI-written specs come out bloated, so we went back to the source: the method layer is being rebuilt from the core books on BDD, DDD and TDD, and its first step already runs with Claude on real product ideas. Next, that method goes into the app.

Contact

Tri Nguyen, founder · admin@tnexa.org