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import { mergeDeepLeft } from './mergeDeepLeft';
it('takes two objects, recursively merges their own properties and returns a new object', () => {	const a = { w: 1, x: 2, y: { z: 3 } };	const b = { a: 4, b: 5, c: { d: 6 } };	expect(mergeDeepLeft(a, b)).toEqual({		w: 1,		x: 2,		y: { z: 3 },		a: 4,		b: 5,		c: { d: 6 },	});});
it('overrides properties in the second object with properties in the first object', () => {	const a = { a: { b: 1, c: 2 }, y: 0 };	const b = { a: { b: 3, d: 4 }, z: 0 };	expect(mergeDeepLeft(a, b)).toEqual({ a: { b: 1, c: 2, d: 4 }, y: 0, z: 0 });});
it('is not destructive', () => {	const a = { w: 1, x: { y: 2 } };	const res = mergeDeepLeft(a, { x: { y: 3 } });	expect(a).not.toBe(res);	expect(a.x).not.toBe(res.x);	expect(res).toEqual({ w: 1, x: { y: 2 } });});
it('reports only own properties', () => {	const a = { w: 1, x: { y: 2 } };	function Cla() {}	Cla.prototype.y = 5;	expect(mergeDeepLeft({ x: new Cla() }, a)).toEqual({ w: 1, x: { y: 2 } });	expect(mergeDeepLeft(a, { x: new Cla() })).toEqual({ w: 1, x: { y: 2 } });});