react-day-picker/src/helpers/getWeekdays.test.ts

Customizable Date Picker for React

import { es } from "date-fns/locale/es";

import { DateLib, defaultDateLib } from "../classes/DateLib";

import { getWeekdays } from "./getWeekdays";

let result: Date[];

describe("when rendered without a locale", () => {
  beforeEach(() => {
    result = getWeekdays(defaultDateLib);
  });
  test("should return 7 days", () => {
    expect(result).toHaveLength(7);
  });
  test("should return Sunday as first day", () => {
    expect(result[0]).toBeSunday();
  });
});

describe.each<0 | 1 | 2 | 3 | 4 | 5 | 6>([0, 1, 2, 3, 4, 5, 6])(
  "when week start on %s",
  (weekStartsOn) => {
    beforeEach(() => {
      result = getWeekdays(new DateLib({ locale: es, weekStartsOn }));
    });
    test("the first date should be weekStartsOn", () => {
      expect(result[0].getDay()).toBe(weekStartsOn);
    });
  }
);

describe("when using ISO week", () => {
  beforeEach(() => {
    result = getWeekdays(
      new DateLib({ locale: es, weekStartsOn: 3 }),
      true,
      undefined
    );
  });
  test("should return Monday as first day", () => {
    expect(result[0]).toBeMonday();
  });
});