Simple, type safe* object factories for JavaScript tests. (*with TypeScript)
You need to write maintainable tests for JavaScript. The code depends on specific entity types defined in the data model. These entities might initially get stubbed out in tests (Mocha, Jest, etc) as plain objects. As complexity grows, you move to factory functions (or another package that does this) to avoid the duplication. A new column gets added, an old one gets removed or maybe an entirely new entity is added. The breaking change isn't noticed until the entire test suite runs (or maybe never).
cooky-cutter is a light package
that leverages TypeScript to define and create factories. Simply pass the type
as a generic (assuming you already have a type or interface defined for each
entity type). Whenever the entity type changes, the factories become invalid!
npm install --save-dev cooky-cutter
# or
yarn add --dev cooky-cutterFor more documentation and examples, read the full documentation.
import { define, random, sequence } from "cooky-cutter";
// Define an interface (or type) for the entity
interface User {
id: number;
firstName: string;
lastName: string;
age: number;
}
// Define a factory that represents the defined interface
const user = define<User>({
id: random,
firstName: i => `Bob #${i}`,
lastName: "Smith",
age: sequence
});
// Invoke the factory a few times
console.log(user());
// => { id: 980711200, firstName: 'Bob #1', lastName: 'Smith', age: 1 }
console.log(user());
// => { id: 1345667839, firstName: 'Bob #2', lastName: 'Smith', age: 2 }
console.log(user());
// => { id: 796816401, firstName: 'Bob #3', lastName: 'Smith', age: 3 }