A guide to Behavior-Driven Development, a way to describe software behavior in examples that both technical and non-technical people can read. It uses Gherkin scenarios with Given, When, and Then steps, plus Cucumber to run them.

Use it to write feature files, implement Cucumber step definitions, prepare acceptance scenarios, and review BDD test quality.

It helps teams agree on expected behavior and diagnose whether a failed scenario comes from the product or its test steps.

bdd-testing — Skill for Claude Code and Codex by pantheon-org

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo

git clone --depth 1 https://github.com/pantheon-org/tekhne

agentmods

npx agentmods add skills/pantheon-org/tekhne/bdd-testing

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/pantheon-org/tekhne/bdd-testing/github.svg)](https://agentmods.dev/skills/pantheon-org/tekhne/bdd-testing)

Your own site

<a href="https://agentmods.dev/skills/pantheon-org/tekhne/bdd-testing"><img src="https://agentmods.dev/badge/skills/pantheon-org/tekhne/bdd-testing/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/pantheon-org/tekhne/bdd-testing"><img src="https://agentmods.dev/badge/skills/pantheon-org/tekhne/bdd-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 76 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 979 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 6 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium MCP Rug Pull · line 31
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 40
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 48
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 56
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 64
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 74
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00076	$0.00979
Opus 5	$0.00038	$0.00490
Sonnet 5	$0.00015	$0.00196
Haiku 4.5	$0.00008	$0.00098

Measured 9d ago against content hash 5cbbea37253a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

bdd-testing scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/testing/bdd-testing/SKILL.md · 152 lines

How it starts

The opening of the file, as written. The whole thing — 152 lines — stays where its author put it; the contents beside it link to each section on GitHub.

BDD Testing

When to Use

Use this skill when behavior needs to be specified and validated in shared, business-readable scenarios.

When Not to Use

Do not use BDD feature files for low-level unit behavior that is internal and not stakeholder-facing.

Core Principles

Specify observable behavior, not implementation details.
Keep a shared language across product, engineering, and QA.
Scenarios should be deterministic and independently executable.
Feature files should remain readable by non-developers.

Deterministic Workflow

Align on examples in a Three Amigos discussion.
Write scenarios in Gherkin using Given/When/Then.
Implement step definitions that map to business language.
Execute Cucumber and review failures by scenario intent.
- Validation checkpoint: If scenarios fail due to incorrect business logic, loop back to step 2 to clarify requirements.
- Validation checkpoint: If scenarios fail due to step definition errors or missing steps, loop back to step 3 to fix implementation.
- Error recovery: Run npx cucumber-js --dry-run to identify missing step definitions before full execution.
- Error recovery: For async timing issues, verify step definitions properly await promises.
Refactor scenarios and steps to remove duplication.

Quick Commands

Run all feature tests

npx cucumber-js features

Expected result: scenario pass/fail summary and non-zero exit on failures.

Dry-run to detect missing step definitions

npx cucumber-js --dry-run features

Expected result: undefined steps listed without full execution.

Run a tagged subset

npx cucumber-js --tags "@smoke and not @wip"

Expected result: only matching scenarios execute.

Generate JSON report

npx cucumber-js --format json:reports/cucumber-report.json

Expected result: machine-readable execution report for CI/reporting.

Troubleshoot common Cucumber failures

Step definition mismatch:

Read the full file on GitHub · 152 lines

Files

What ships with it

30 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

9d ago First seen · 152 lines · 76 tokens per session scan A 5cbbea37253a

Subscribe to this mod's changes

bdd-testing is a skill published in the GitHub repository pantheon-org/tekhne (10 stars, last pushed yesterday), licensed MIT. It adds 76 tokens to every session and 979 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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