Duck Test - API Contract Enforcement

If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck

ducktest reads what an API should do, hits it and compares the result. If it looks the same, Jest test passes.

It aims at defining API contracts in a declarative way, used for both cross-functionnal collaboration AND System Integration Testing. In other words, a single definition should be great to share with your fellow frontend colleagues, while still being used by Jest for delightful testing.

Disclaimer: project at tinkering around stage. There's no generic way to install and use it outside of this repository at the moment. Mostly because I don't want to waste time on the CLI UX while the testing API is not even figured out yet.

Testing is powered by Jest for its extensive matchers library and great output. API schema validation is powered by Joi as the most comprehensive and expressive validation library around.

Example - fixer.io API

Configuration as Code:

const Joi = require('joi')

const scenario = {
  query: {
    access_key: process.env.FIXER_API_KEY,
    base: 'USD',
    symbols: 'GBP,JPY'
  },

  response: {
    code: 200,
    payload: Joi.object({
      success: true,
      timestamp: Joi.date().timestamp(),
      base: Joi.string(),
      date: Joi.date(),
      rates: Joi.object({
        GBP: Joi.number(),
        JPY: Joi.number(),
    })
  } 
}

module.exports = {
  project: 'Example',
  domain: 'https://data.fixer.io',
  scope: 'exchange rate',

  method: 'GET',
  endpoint: '/api/latest',

  scenarios: [scenario],
}

Usage

Contract example: ./contracts/coincap.

Tested under node v14.17.5 (LTS at I write this) and npm 7.20.6.

# install
npm install

# test
npm test

# voila

Possible future evolution:

# search configurations and generate tests
npx ducktest discover ./contracts

ls __tests__/sit/
# ... code generated ...

# run the test suite
ducktest coincoin --environment staging

xav-b/ducktest

Duck Test - API Contract Enforcement

Example - fixer.io API

Usage