type-fest/test-d/simplify-deep.ts

import {expectType} from 'tsd';
import type {SimplifyDeep} from '../index';

type Properties1 = {
	height: number;
	position: {
		top: number;
		bottom: number;
	};
};

type Properties2 = {
	width: number;
	position: {
		left: number;
		right: number;
	};
};

// Flatten the type output to improve type hints shown in editors.
declare const flattenProperties: {
	height: number;
	width: number;
	position: {
		top: number;
		bottom: number;
		left: number;
		right: number;
	};
};

expectType<SimplifyDeep<Properties1 & Properties2>>(flattenProperties);

// Array
type ArrayType = Array<{
	a: string;
}>;

declare const flattenProperties2: {
	arrayType: Array<{
		a: string;
	}>;
};
expectType<SimplifyDeep<{arrayType: ArrayType}>>(flattenProperties2);