Problem 3: fix the formatting of Canadian Postal Codes

/*******************************************************************************
* Problem 3: fix the formatting of Canadian Postal Codes
*
* A Canadian Postal Code (see https://en.wikipedia.org/wiki/Postal_codes_in_Canada)
* is a 6-character string of the following form:
*
* A1A 1A1
*
* Many databases have postal codes that have been manually entered, and contain
* formatting errors. The fixPostalCode() function takes a possible postal code
* (i.e. a string), attempts to format it, and returns the formatted version.
* However, not all input postal codes can be formatted, and should be rejected
* (see below).
*
* Here are the formatting rules we can fix, and validation checks we can make:
*
* – Remove any leading/trailing whitespace
* – Convert everything to UPPER case letters
* – The fourth character might be a space, a dash (-), or be missing. Make it a space
* – Make sure the order and format of the letters/numbers is correct
*
* There are more than 800K valid postal codes. The first three-characters of
* the postal code is called a “Forward Sortation Area,” and represents a geographic
* region, with the first letter representing a province, or part of a province.
*
* The first character in a postal code can be any letter except D, F, I, O, Q, W, U, Z
*
* The other characters (i.e., letters) in a postal code can be any letter except
* D, F, I, O, Q or U (i.e., W and Z are allowed)
*
* The numbers can be anything between 0 and 9
*
* If the string is not a valid postal code, an Error should be thrown. See
* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/throw.
*
* HINT: use a Regular Expression to help you check for valid characters/numbers
*
* @param {string} postalCode – a possible postal code to be formatted
* @returns {string} – a formatted postal code
******************************************************************************/

function fixPostalCode(postalCode) {
// Replace this comment with your code…
}

Problem test 3

const { fixPostalCode } = require(‘./solutions’);

describe(‘Problem 3 – fixPostalCode() function’, function () {
test(‘leading space is removed’, function () {
const postalCode = ‘ A1A 1A1’;
expect(fixPostalCode(postalCode)).toEqual(‘A1A 1A1’);
});

test(‘trailing space is removed’, function () {
const postalCode = ‘A1A 1A1 ‘;
expect(fixPostalCode(postalCode)).toEqual(‘A1A 1A1’);
});

test(‘an internal space is added if missing’, function () {
const postalCode = ‘A1A1A1’;
expect(fixPostalCode(postalCode)).toEqual(‘A1A 1A1’);
});

test(‘an internal space is added instead of a dash’, function () {
const postalCode = ‘A1A-1A1’;
expect(fixPostalCode(postalCode)).toEqual(‘A1A 1A1’);
});

test(‘lowercase letters are converted to UPPER case’, function () {
const postalCode = ‘a1a 1a1’;
expect(fixPostalCode(postalCode)).toEqual(‘A1A 1A1’);
});

test(‘a postal code with too many characters throws an error’, function () {
const invalidPostalCode = ‘A1A 1A11’;
expect(() => fixPostalCode(invalidPostalCode)).toThrow();
});

test(‘a postal code with too few characters throws an error’, function () {
const invalidPostalCode = ‘A1A’;
expect(() => fixPostalCode(invalidPostalCode)).toThrow();
});

test(‘a postal code that starts with an invalid character throws an error’, function () {
// D, F, I, O, Q, W, U, Z are all invalid in the first position
expect(() => fixPostalCode(‘D1A 1A1’)).toThrow();
expect(() => fixPostalCode(‘F1A 1A1’)).toThrow();
expect(() => fixPostalCode(‘I1A 1A1’)).toThrow();
expect(() => fixPostalCode(‘O1A 1A1’)).toThrow();
expect(() => fixPostalCode(‘Q1A 1A1’)).toThrow();
expect(() => fixPostalCode(‘W1A 1A1’)).toThrow();
expect(() => fixPostalCode(‘U1A 1A1’)).toThrow();
expect(() => fixPostalCode(‘Z1A 1A1’)).toThrow();
});

test(‘a postal code with a non-digit in the second position throws an error’, function () {
expect(() => fixPostalCode(‘DZA 1A1’)).toThrow();
});

test(‘a postal code with an invalid character in the third position throws an error’, function () {
// D, F, I, O, Q, U are all invalid in the first position
expect(() => fixPostalCode(‘A1D 1A1’)).toThrow();
expect(() => fixPostalCode(‘A1F 1A1’)).toThrow();
expect(() => fixPostalCode(‘A1I 1A1’)).toThrow();
expect(() => fixPostalCode(‘A1O 1A1’)).toThrow();
expect(() => fixPostalCode(‘A1Q 1A1’)).toThrow();
// W is valid in this position
expect(fixPostalCode(‘A1W 1A1’)).toEqual(‘A1W 1A1’);
expect(() => fixPostalCode(‘A1U 1A1’)).toThrow();
// Z is valid in this position
expect(fixPostalCode(‘A1Z 1A1’)).toEqual(‘A1Z 1A1’);
});

test(‘a postal code with a non-space or invalid character in the fourth position throws an error’, function () {
expect(() => fixPostalCode(‘A1A!1A1’)).toThrow();
expect(() => fixPostalCode(‘A1A 1A1’)).toThrow();
});

test(‘a postal code with a non-digit in the fifth position throws an error’, function () {
expect(() => fixPostalCode(‘AZAAA1’)).toThrow();
expect(() => fixPostalCode(‘AZA A1’)).toThrow();
});

test(‘a postal code with an invalid character in the sixth position throws an error’, function () {
// D, F, I, O, Q, U are all invalid in the sixth position
expect(() => fixPostalCode(‘A1A 1D1’)).toThrow();
expect(() => fixPostalCode(‘A1A 1F1’)).toThrow();
expect(() => fixPostalCode(‘A1A 1I1’)).toThrow();
expect(() => fixPostalCode(‘A1A 1O1’)).toThrow();
expect(() => fixPostalCode(‘A1A 1Q1’)).toThrow();
// W is valid in this position
expect(fixPostalCode(‘A1A 1W1’)).toEqual(‘A1A 1W1’);
expect(() => fixPostalCode(‘A1A 1U1’)).toThrow();
// Z is valid in this position
expect(fixPostalCode(‘A1A 1Z1’)).toEqual(‘A1A 1Z1’);
});

test(‘a postal code with a non-digit in the seventh position throws an error’, function () {
expect(() => fixPostalCode(‘A1A AAG’)).toThrow();
expect(() => fixPostalCode(‘A1A A1-‘)).toThrow();
});
});