Advent of PBT 2021 - Day 18

Advent of PBT 2021 — Learn how to use property based testing and fast-check through examples

Our algorithm today is: isPalindrome.
It comes with the following documentation and prototype:

/**
 * A string s is said to be a palindrome
 * if it reads the same backward and forward
 *
 * @param s - The strings to be assessed
 */
declare function isPalindrome(s: string): boolean;

We already wrote some examples based tests for it:

it("should detect palindromes made of even ascii characters", () => {
  expect(isPalindrome("azza")).toBe(true);
});

it("should detect palindromes made of odd ascii characters", () => {
  expect(isPalindrome("azereza")).toBe(true);
});

it("should detect palindromes made of characters outside of bmp plan", () => {
  expect(isPalindrome("🐱🐴🐱")).toBe(true);
});

it("should detect non palindromes made of even ascii characters", () => {
  expect(isPalindrome("azea")).toBe(false);
});

it("should detect non palindromes made of odd ascii characters", () => {
  expect(isPalindrome("azera")).toBe(false);
});

How would you cover it with Property Based Tests?

In order to ease your task we provide you with an already setup CodeSandbox, with examples based tests already written and a possible implementation of the algorithm: https://codesandbox.io/s/advent-of-pbt-day-18-v924d?file=/src/index.spec.ts&previewwindow=tests

You wanna see the solution? Here is the set of properties I came with to cover today's algorithm: https://dev.to/dubzzz/advent-of-pbt-2021-day-18-solution-28h3

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Back to "Advent of PBT 2021" to see topics covered during the other days and their solutions.

More about this serie on @ndubien or with the hashtag #AdventOfPBT.