README

ProbabilityChecker

Pretty simple probability implementation that can be used for A/B testing. If you have some feature that you want to run on 20% of the requests. This is right tool for you as you do not need to define how many requests there will be in total.

If you provide 0 as a parameter, it will always return false, if you provide 100, it will always return true. Everything in between will be around the number you provided.

Note: This method is not exact but approximation, so if you want 20%, you will get 21%, 23% maybe 18%, but at the end it will be around 20% (the greater number of request, more accurate will be the percentage).

Installation

This library can be installed via composer:

composer require robier/probability-checker

Sample usage

<?php

$probability = new \Robier\ProbabilityChecker(30);

$skipped = 0;
$executed = 0;
for($i = 0; $i < 1000000; $i++) {
    if ($probability->roll()) {
        $executed++;
    } else {
    	$skipped++;
    }
}

$percentageAtTheEndSkipped = round($skipped / ($executed + $skipped), 6) * 100;
$percentageAtTheEndExecuted = round(100 - $percentageAtTheEndSkipped, 6);

echo "Executed $executed and Skipped $skipped \n";
echo "Executed $percentageAtTheEndExecuted% and Skipped $percentageAtTheEndSkipped%";

1st run

Skipped 699978 and Executed 300022 
Skipped 69.9978% and Executed 30.0022%

2nd run

Skipped 699813 and Executed 300187 
Skipped 69.9813% and Executed 30.0187%

3rd run

Skipped 700351 and Executed 299649 
Skipped 70.0351% and Executed 29.9649%

From this you can see that the percentage is not exact, but it is around 30% as we defined.

Methods

We have few methods in the class:

Local development

To run tests locally you can use provided docker setup. Just run:

docker/build

to build the image and then run:

docker/run composer test

to run the tests. If you want to run tests with coverage, you can run:

docker/run composer test:coverage