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Nicolas DUBIEN
Nicolas DUBIEN

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Advent of PBT 2021 - Day 12

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

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

 * Given a string s containing just the characters '(', ')', '{',
 * '}', '[' and ']', determine if the input string is valid.
 * @param expression -
 * @returns
 * An input string is valid if:
 * Open brackets must be closed by the same type of brackets.
 * Open brackets must be closed in the correct order.
declare function validParentheses(expression: string): boolean;
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We already wrote some examples based tests for it:

it("should accept simple expressions", () => {

it("should accept nested expressions", () => {

it("should accept expressions with multiple groups", () => {

it("should reject wrong matching bracket", () => {

it("should reject unbalanced brackets with more closing", () => {

it("should reject unbalanced brackets with more opening", () => {

it("should reject bad nesting", () => {
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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:

You wanna see the solution? Here is the set of properties I came with to cover today's algorithm:

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.

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