Luis Presa Collada Pablo Caal Surez Sofa Garca Barbs Daniel Finca - - PowerPoint PPT Presentation

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Luis Presa Collada Pablo Caal Surez Sofa Garca Barbs Daniel Finca - - PowerPoint PPT Presentation

Dec 25, 2023 426 likes •841 views

Luis Presa Collada Pablo Caal Surez Sofa Garca Barbs Daniel Finca Martnez Introduction Some definitions Property testing Property, Law or Invariant Test generation Non-deterministic test execution Property testing /

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Luis Presa Collada Pablo Cañal Suárez Sofía García Barbés Daniel Finca Martínez

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Introduction

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Some definitions

▪ Property testing ▪ Property, Law or Invariant ▪ Test generation ▪ Non-deterministic test execution

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Property testing / Generative testing

▪ Writing code: Solving a problem. ▪ Writing tests: Checking whether or not our solution is valid ▪ Integer array sorting function

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Property / Law / Invariant

▪ Characteristic(s) that qualify the result of the execution of certain piece of code. ▪ Some are valid in many cases. Some are not. ▪ Previous integer array sorting function properties:

– Sorting an array would never modify its content (add, remove, change elements). – Sorting an already sorted array does nothing to it. – Sorting a sequence of numbers results in an ordered list (Quite obvious BTW).

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Test generation => Ad-hoc generators

▪ Well, I have the properties. What do I do now?

– Good question by the way! ( :

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NDE => Non-deterministic execution

▪ Randomness is a pain in the… Yeah. ▪ Sometimes test pass. Some others… well you just simply don’t have a clue about what happened.

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Why is it awesome?

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Three main features...

▪ Coverage ▪ Reproducible ▪ Shrink

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Traditional testing...? Sure?

▪ Coverage function serialize<T>(instance: T, params: Parameters): string { /* code */ }

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Discover uncovered code paths!

▪ Coverage test( ‘Should be able to read itself’ , () => { fc.assert( fc.property( fc. jsonObject(), (instance, params) => { expect(deserialize( serialize(instance, params))).toEqual( instance); }) ) });

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Replay the same test!

▪ Reproducible Error: Property failed after 1 tests ( seed: 1527423434693, path: "0:0:0“ ): ["","",""] Shrunk 2 time(s) Got error: Property failed by returning false

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Replay the same test!

▪ Reproducible test('the failing test', () => fc.assert ( fc.property ( // check method ), { seed: 1527423434693, // seed and path taken from the previous slide path: "0:0:0" } ));

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Understand your errors...

▪ Shrink test('the failing test', () => fc.assert ( fc.property ( // check method ), { verbose: true } ));

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Understand your errors...

▪ Shrink Error: Property failed after 1 tests ( seed: 1527423434693, path: "0:0:0“ ): ["","",""] Shrunk 2 time(s) Got error: Property failed by returning false Encountered failures were:

  • ["", "JeXPqIQ6”, ">q"]
  • ["", "", ">q"]
  • ["", "", ""]
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Who could be interested?

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Stakeholders

Nicolas Dubien The GitHub team

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Stakeholders You as a developer!

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Packages using Fast-check!

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How to Fast-Check

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Hang on! Configure jest script

"scripts": { "test": "jest" }, "jest": { "moduleFileExtensions": ["ts", "tsx", "js"], "globals": {"ts-jest": {"tsConfig": "tsconfig.json"}}, "transform": {"^.+\\.(ts|tsx)$": "ts-jest"}, "testMatch": ["**/specs/*.+(ts|tsx|js)"] },

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And finally… npm install --save-dev fast-check

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Let’s go slow, for now

Method to test Test Method

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Boring stuff, right? Fast! Check this!

▪ Numbers: (and you can bound them!)

– Natural – Negative – Floating point

▪ Random strings:

– Ascii, Unicode. – Length bounded – Char bit size

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Not convinced yet? More random Strings!!

▪ Json structure

  • >

.json(maxLength) ▪ Ipv4, Ipv6

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.ipv4() .ipv6() ▪ URLs

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.webUrl() ▪ Email addresses

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.emailAddress() ▪ UUID

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.uuid() .uuidV(version)

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More “normal” things

▪ Fixed contant

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.constant(value) ▪ Picked constant

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.oneOf(array[value]) ▪ Array: of anArbitrary. ▪ Subarray: picks elements from an array. You may shuffle. ▪ Set: Unique values of Arbitrary.

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anything(settings:ObjectConstraints.Settings)

  • You need an input
  • You configure it
  • You use the function
  • You have your test :D
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RECUR_RECUR__RECURSION__SION_SION

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Crazy, random, and recursive.

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Don’t understimate its power

▪ Transform and derive Arbitraries:

– Map – Filter

▪ Commands (PreCondition -> Execution -> PostCondition) ▪ Support for asynchronous :

– Command – Arbitraries – Handle Race Conditions

▪ Shedulers ▪ Wrap calls.

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Someone said API?

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{api}

▪ Arbitraty

export declare abstract class Arbitrary<T>

▪ Shrinkable

export declare class Shrinkable<T, TShrink extends T = T>

▪ anything(settings?) ▪ asciiString(minLength?, maxLength?) ▪ double() ▪ float() ▪ …

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Quality Attributes

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Why use it?

▪ Offers plenty of types ▪ Extendable ▪ Filtering options ▪ Adds debugging advantages ▪ Race conditions detection

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Fast (and active) Check

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Fast (and active) Check

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Fast Releases

1.23.0

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Thanks for fast- checking with us!!