bdd-regression-test-generator

An autonomous agent that analyzes REST API endpoints and OpenAPI/Swagger service contracts to generate:

• BDD Gherkin specifications (.feature files) describing all happy-path and edge-case scenarios.
• TypeScript regression test scripts (Jest + Playwright-ready) ready to run against real services.

It exposes two interfaces:

Interface	Description
CLI	bdd-gen generate --input <spec> --output <dir>
MCP Server	Model Context Protocol server exposable to any MCP-aware host (e.g. IBM Bob, Claude Desktop)

---

Features

• Parses OpenAPI 3.x and Swagger 2.0 contracts (JSON or YAML).
• Extracts all paths, HTTP methods, parameters, request bodies, and response schemas.
• Generates one .feature file per endpoint tag group.
• Generates one *.spec.ts file per endpoint tag group with fully typed Jest test cases.
• Supports custom base-URL injection at generation time.
• MCP server exposes analyze_contract, generate_gherkin, and generate_tests tools.

---

Installation

npm install
npm run build

To use as a global CLI after building:

npm link

---

CLI Usage

# Generate both Gherkin and Jest tests from an OpenAPI YAML spec
bdd-gen generate --input ./petstore.yaml --output ./generated --baseUrl https://api.example.com

# Generate only Gherkin feature files
bdd-gen generate --input ./petstore.json --output ./generated --only gherkin

# Generate only Jest test scripts
bdd-gen generate --input ./petstore.json --output ./generated --only jest

# Analyze a contract and print a summary (no file generation)
bdd-gen analyze --input ./petstore.yaml

CLI Options

Option	Alias	Description	Default
--input <path>	-i	Path to the OpenAPI/Swagger contract file	required
--output <dir>	-o	Directory where generated files will be written	./generated
--baseUrl <url>	-b	Base URL to embed in the generated test files	http://localhost:3000
--only <type>		Generate only gherkin or jest (omit for both)	both
--verbose	-v	Enable verbose logging	false

---

MCP Server

Start the MCP server with:

npm run mcp

The server registers the following tools:

analyze_contract

Parses an OpenAPI/Swagger contract from a file path or raw JSON/YAML string.

Input:

{ "source": "./petstore.yaml" }

Output: A structured ContractSummary JSON object with paths, methods, parameters, and schemas.

---

generate_gherkin

Generates Gherkin .feature content from a parsed contract.

Input:

{
  "source": "./petstore.yaml",
  "outputDir": "./generated"
}

Output: List of written .feature file paths.

---

generate_tests

Generates TypeScript Jest test scripts from a parsed contract.

Input:

{
  "source": "./petstore.yaml",
  "outputDir": "./generated",
  "baseUrl": "https://api.example.com"
}

Output: List of written .spec.ts file paths.

---

Project Structure

bdd-regression-test-generator/
├── src/
│   ├── parser/
│   │   └── contract-analyzer.ts   # OpenAPI/Swagger parser and extractor
│   ├── generator/
│   │   ├── gherkin-builder.ts     # Gherkin .feature file builder
│   │   └── jest-builder.ts        # TypeScript Jest spec builder
│   ├── mcp/
│   │   └── server.ts              # MCP server exposing generation tools
│   └── cli.ts                     # Commander-based CLI entry point
├── tests/
│   └── generator.test.ts          # Unit tests for parser and generators
├── dist/                          # Compiled output (after build)
├── package.json
├── tsconfig.json
└── README.md

---

Running Tests

npm test

With coverage:

npm run test:coverage

---

Example: Generated Gherkin

Feature: Pets

  Background:
    Given the API base URL is "https://api.example.com"

  Scenario: GET /pets - list all pets - success
    Given I have valid authentication credentials
    When I send a GET request to "/pets"
    Then the response status code should be 200
    And the response body should match the "PetList" schema

  Scenario: GET /pets - list all pets - unauthorized
    Given I have invalid or missing authentication credentials
    When I send a GET request to "/pets"
    Then the response status code should be 401

---

Example: Generated Jest Test

import axios from 'axios';

const BASE_URL = 'https://api.example.com';

describe('Pets', () => {
  describe('GET /pets', () => {
    it('should return 200 for a valid request', async () => {
      const response = await axios.get(`${BASE_URL}/pets`);
      expect(response.status).toBe(200);
    });
  });
});

---

License

MIT