Spread operator vs lodash's cloneDeep()

cloneTest.js

// This is an illustration of when NOT to use the spread operator to copy variables.
// Check https://codesandbox.io/s/6w749171mz for a working copy of the code

import { cloneDeep } from "lodash";
import {
  getDrinkNutrientsFromResult,
  mapRecipesToNutrients
} from "../nutrition";

describe("helper methods", () => {
  const recipes = [
    {
      id: 1,
      state: "ready",
      createdAt: "2019-03-19T01:01:01.000Z",
      nutrients: [
        { key: "chromium", value: 1116.47 },
        { key: "biotin", value: 0.01 }
      ]
    },
    {
      id: 2,
      state: "in_progress",
      createdAt: "2019-03-19T01:01:01.000Z",
      nutrients: [
        { key: "chromium", value: 1116.47 },
        { key: "biotin", value: 0.01 }
      ]
    }
  ];
  const expectedData = [
    { key: "biotin", unit: "mg", value: 0.01 },
    { key: "chromium", unit: "mg", value: 1116.47 }
    // ...
  ];

  const nutrientNames = [
    "biotin",
    "chromium"
    // ...
  ];

  let recipesList, expected;
  beforeEach(() => {
    // cloneDeep will copy all the elements by value recursively, instead of passing them by reference
    //
    recipesList = cloneDeep(recipes);
    expected = cloneDeep(expectedData);

    // The tests would break, because even though recipesList is a new variable
    // teh rest operator will copy all the elements by REFERENCE
    //
    // recipesList = [...recipes];
  });

  it("should get the nutrients from a recipe", () => {
    // mutates the element
    recipesList.find(recipe => recipe.state === "in_progress").createdAt =
      "2019-03-20T22:13:13.889Z";

    expect(getDrinkNutrientsFromResult(recipesList)).toEqual(expected);
  });

  it("should behave gracefully when an expected element is not in the recipe", () => {
    // mutates the elements
    recipesList.find(r => r.id === 1).nutrients[0] = null;
    expected.find(n => n.key === "chromium").value = 0;

    expect(getDrinkNutrientsFromResult(recipesList)).toEqual(expected);
  });

  // putting this test last will make it fail if using the spread operator
  // because chromium's value has been modified to 0 from line 67.
  // cloneDeep() clones the elements too, this way the problem doesn't happen anymore
  //
  it("should map recipes to nutrients correctly", () => {
    expect(mapRecipesToNutrients(recipesList, nutrientNames)).toEqual(expected);
  });
});