card-validator/src/__tests__/expiration-year.ts

A library for validating credit card fields

import { expirationYear, ExpirationYearVerification } from "../expiration-year";

const currentYear = new Date().getFullYear();

function yearsFromNow(fromNow: number, digits?: number): string {
  let result = String(currentYear + fromNow);

  if (digits === 2) {
    result = result.substr(2, 2);
  }

  return result;
}

describe("expirationYear", () => {
  const FALSE_VALIDATION = {
    isValid: false,
    isPotentiallyValid: false,
    isCurrentYear: false,
  };

  describe.each([
    [
      "returns false if not a string",
      [
        [[], FALSE_VALIDATION],
        [{}, FALSE_VALIDATION],
        [null, FALSE_VALIDATION],
        [undefined, FALSE_VALIDATION], // eslint-disable-line no-undefined
        [Infinity, FALSE_VALIDATION],
        [0 / 0, FALSE_VALIDATION],
        [0, FALSE_VALIDATION],
        [1, FALSE_VALIDATION],
        [2, FALSE_VALIDATION],
        [12, FALSE_VALIDATION],
        [-1, FALSE_VALIDATION],
        [-12, FALSE_VALIDATION],
      ],
    ],

    [
      "returns false for malformed strings",
      [
        ["foo", FALSE_VALIDATION],
        ["1.2", FALSE_VALIDATION],
        ["1/20", FALSE_VALIDATION],
        ["1 2", FALSE_VALIDATION],
        ["1 ", FALSE_VALIDATION],
        [" 1", FALSE_VALIDATION],
        ["20015", FALSE_VALIDATION],
      ],
    ],

    [
      "returns the appropriate values for incomplete strings",
      [
        [
          "",
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          "2",
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          "9",
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          "200",
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          "123",
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
        [
          "20",
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
      ],
    ],

    [
      "accepts four-digit years",
      [
        [
          yearsFromNow(0),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: true },
        ],
        [
          yearsFromNow(-5),
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
        [
          yearsFromNow(5),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(10),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(11),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(12),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(19),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(20),
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
        [
          yearsFromNow(25),
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
        [
          yearsFromNow(33),
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
      ],
    ],

    [
      "accepts two-digit years",
      [
        [
          yearsFromNow(0, 2),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: true },
        ],
        [
          yearsFromNow(-5, 2),
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
        [
          yearsFromNow(5, 2),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(10, 2),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(11, 2),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(12, 2),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(19, 2),
          { isValid: true, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(20, 2),
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
        [
          yearsFromNow(25, 2),
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
        [
          yearsFromNow(33, 2),
          { isValid: false, isPotentiallyValid: false, isCurrentYear: false },
        ],
      ],
    ],

    /*
     *  This doesn't take 20xx -> 21xx into account, but probably YAGNI
     *  (with apologies to whoever is possibly looking at this legacy
     *  code long after we're dead
     *  */
    [
      "accepts three-digit years",
      [
        [
          yearsFromNow(-3).slice(0, 3),
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(-1).slice(0, 3),
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(0).slice(0, 3),
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(1).slice(0, 3),
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(5).slice(0, 3),
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(11).slice(0, 3),
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(17).slice(0, 3),
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
        [
          yearsFromNow(23).slice(0, 3),
          { isValid: false, isPotentiallyValid: true, isCurrentYear: false },
        ],
      ],
    ],
  ] as Array<[string, Array<[unknown, ExpirationYearVerification]>]>)(
    "%s",
    (description, tests) => {
      it.each(tests)("parses %s to be %p", (exp, meta) => {
        expect(expirationYear(exp)).toEqual(meta);
      });
    },
  );

  it("defaults maxElapsedYear is 19", () => {
    expect(expirationYear(yearsFromNow(19))).toEqual({
      isValid: true,
      isPotentiallyValid: true,
      isCurrentYear: false,
    });
    expect(expirationYear(yearsFromNow(20))).toEqual({
      isValid: false,
      isPotentiallyValid: false,
      isCurrentYear: false,
    });
  });

  it("accepts maxElapsedYear", () => {
    expect(expirationYear(yearsFromNow(20), 20)).toEqual({
      isValid: true,
      isPotentiallyValid: true,
      isCurrentYear: false,
    });
    expect(expirationYear(yearsFromNow(21), 20)).toEqual({
      isValid: false,
      isPotentiallyValid: false,
      isCurrentYear: false,
    });
  });
});