Part Factory test entity factories

Part Factory is a minimalist object factory pattern for TypeScript. It helps you create strongly typed factories with useful default value generation, then override those defaults as needed in each test case.

npm@kensio/part-factory npm package

GitHubKensioSoftware/part-factory GitHub repo

Installation

npm install -D @kensio/part-factory

Usage

Suppose you have an object with this structure, and you want to generate valid instances for tests:

interface Foo { name: string; size: number; }

Part Factory lets you define reusable factories for those objects, with strongly typed defaults and strongly typed overrides.

Create a factory with suitable defaults, then override only the values that matter for the current test.

import { StaticFactory } from "@kensio/part-factory";

interface Foo {
  name: string;
  size: number;
}

const fooFactory = new StaticFactory({
  name: "Foobar",
  size: 10,
});

const defaultFoo = fooFactory.make();
// { name: "Foobar", size: 10 }
const myFoo = fooFactory.make({ size: 20 });
// { name: "Foobar", size: 20 }

Overrides are partial through the object structure, so you can override a nested value without replacing the whole tree.

const userProfile = userProfileFactory.make({
  contact: { address: { city: "Manchester" } },
});

Factories

StaticFactoryCreates complete items from one static set of default values

DynamicFactoryCreates complete items from a function that builds default values

VariantFactoryCreates complete items from another factory with preset overrides

MappedFactoryCreates output values by mapping a completed input object