@grohden/create-mock-fn

A simple fn to create mock fns given previously generated types.

Installation

Hey, you can also just copy this to your project if you're ok with it :D

My initial gist is here, either copy it or the one in the src dir

Install with:

npm install --save-dev @grohden/create-mock-fn

Usage

This was created with codegen for types in mind, it should work well if you generate types from open api/swagger definitions or from graphql codegen.

Basic Example

import { createMockFn } from '@grohden/create-mock-fn';

type User = {
  id: string;
  name: string;
  role: 'admin' | 'user';
};

// Define your mock factory
export const mockUser = createMockFn(
  (): User => ({
    id: 'user-123',
    name: 'John Doe',
    role: 'user',
  })
);

// Use it in tests
const defaultUser = mockUser(); 
// { id: 'user-123', name: 'John Doe', role: 'user' }

const customUser = mockUser({ name: 'Jane Doe' }); 
// { id: 'user-123', name: 'Jane Doe', role: 'user' }

Using Traits

Traits allow you to define named variations of your mock.

export const mockUser = createMockFn(
  (): User => ({
    id: 'user-123',
    name: 'John Doe',
    role: 'user',
  }),
  {
    admin: () => ({ role: 'admin' }),
    premium: () => ({ name: 'Premium User' }),
  }
);

// Apply traits
const admin = mockUser({}, ['admin']);
// { id: 'user-123', name: 'John Doe', role: 'admin' }

const premiumAdmin = mockUser({ id: 'custom-id' }, ['admin', 'premium']);
// { id: 'custom-id', name: 'Premium User', role: 'admin' }

API

createMockFn(makeDefaults, traitMap?)

• makeDefaults: A function that returns the default object structure.
• traitMap (optional): An object where keys are trait names and values are functions returning partial overrides.

Returns a function: (overrides?, traits?) => T

License

ISC