# Bdd

> Behavior-Driven Development as a collaboration and specification practice, with pytest-bdd and behave as the bundled automation references. Use when defining behavior through concrete examples or acceptance criteria, writing or reviewing Gherkin .feature files, wiring pytest-bdd or behave step definitions, or checking that tests still express business behavior rather than implementation.

- **Type:** Skill
- **Install:** `agentstack add skill-yassimba-loom-bdd`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [Yassimba](https://agentstack.voostack.com/s/yassimba)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [Yassimba](https://github.com/Yassimba)
- **Source:** https://github.com/Yassimba/loom/tree/main/skills/bdd

## Install

```sh
agentstack add skill-yassimba-loom-bdd
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Behavior-Driven Development

BDD builds shared understanding of a problem through concrete examples, written in business language, agreed before implementation. The examples become executable specifications; running them drives the code. The order is fixed: **conversation first, capture second, automation last**. A team running Gherkin without the conversation has test automation, not BDD.

Two automation layers are bundled: [pytest-bdd](references/pytest-bdd.md) and [behave](references/behave.md). The practice and the Gherkin carry to any stack — see [Other automation layers](#other-automation-layers).

## Preflight: does this deserve Gherkin?

Gate every "add a BDD test" impulse:

- The behavior is stable and business-meaningful — not scaffolding, framework glue, or an implementation still finding its shape.
- The scenario states a user intent or observable outcome, not internal mechanics.
- The sentence helps someone imagine a real use of this project. A scenario that reads as a natural-language translation of a technical test gets rewritten, or dropped in favor of a plain pytest test.

## Workflow

1. **Discover.** Write down Who / What / Why, the business rules, examples, and open questions — before touching a test framework. Done when every rule carries at least one positive and one negative example and every unknown is a recorded question rather than a guess. Working solo, simulate the Three Amigos (business, development, quality) and mark which points are inference needing user confirmation. Detail and templates: [practice.md](references/practice.md).
2. **Formulate.** Draft Gherkin — `Given` context, `When` event, `Then` observable outcome — in domain language. Run every scenario through the quality gate below before writing any glue code. Syntax and style: [gherkin.md](references/gherkin.md).
3. **Automate** — only when the user asks for implementation. The framework is a project fact — check the declared dependencies for `behave` or `pytest-bdd` (a `features/steps/` tree with `environment.py` means behave) and join what is there. Only greenfield picks: pytest-bdd when the project already runs pytest (the usual Python default), behave when feature files should run standalone. Mechanics: [pytest-bdd.md](references/pytest-bdd.md) / [behave.md](references/behave.md). Bind scenarios, watch the run fail first, write the smallest code that passes.
4. **Refactor.** Keep scenario language stable while extracting helpers and fixtures; add boundary examples and counterexamples; report the red→green evidence and unresolved questions.

A review-only request ("review this Gherkin", "is this good BDD?") stops after step 2 plus the checklist in [gherkin.md](references/gherkin.md): report findings and the smallest corrections, change no files.

## Gherkin quality gate

Every scenario passes all six before glue code:

1. **One observable behavior** — the scenario explains a rule, boundary, or outcome.
2. **Domain language** — readable with business vocabulary alone; free of URLs, selectors, table columns, class names, HTTP details.
3. **Concrete, not technical** — real roles, amounts, dates, states; never `user1`, `foo`, or "the result is correct".
4. **Clean semantics** — `Given` is context, `When` is one event, `Then` asserts an externally observable result.
5. **Short and independent** — 3–5 steps; runnable in any order; `Background`, `Examples`, and tables carry only necessary meaning.
6. **Failing wording goes back** — a scenario that needs explanation, or is expressible only through implementation detail, returns to Discovery. Rewording beats patching it in glue.

## Other automation layers

pytest-bdd and behave are reference implementations, not the definition of BDD. On another stack or language, everything except the two framework files applies unchanged: keep the workflow and the Gherkin, swap the glue layer, and pull binding mechanics from that framework's docs.

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [Yassimba](https://github.com/Yassimba)
- **Source:** [Yassimba/loom](https://github.com/Yassimba/loom)
- **License:** Apache-2.0

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-yassimba-loom-bdd
- Seller: https://agentstack.voostack.com/s/yassimba
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.