README.md

VariantRetriever

VariantRetriever is a minimalist package for feature flagging. It's fast, database free and idempotent library to choose over a set of variants.

Getting Started

First of all, you need to define an Experiment with a name and it variants. Variant requires 2 arguments, a name and a rollout percentage (50% by default). Then create a variant retriever with this experiment and variants, and ask it to retrieve a variant for a resource (in the following code, it's for a user uuid).

$variantRetriever = new VariantRetriever();
$experiment = new Experiment('my-ab-test', ...[new Variant('control1'), new Variant('variant2')]);
$variantRetriever->addExperiment($experiment);

$affectedVariant = $variantRetriever->getVariantForExperiment(new Experiment('my-ab-test'), '77d8a1d5-97ba-42db-a4a7-3b9562f0ff22');

var_dump((string) $affectedVariant); // string(7) "variant2"

Running the Test Suite

VariantRetriever uses Pest PHP as testing framework. Once you have all dependencies installed via composer install, you can run the test suite with:

./vendor/bin/pest

To obtain the code coverage report, you'll need to have xdebug installed. Then, you can run:

./vendor/bin/pest --coverage

And this will give you detailed information about code coverage.

What about speed

VariantRetriever is fast. In our test, we ensure that the retriever is able to get 50 000 variants to randomly generate different identifiables in less than 1 second. Local dev machine can run 500 000 runs in less than a second.

What about randomness

Rows	Rollout	Rollout	Max Rollout difference
1k	50/50	46.5/46.5	3.5%
500k	50/50	49.87/49.87	0.13%
500k	10*10	9.88	0.12%
500k	10/10/80	9.88/9.88/79.92	0.12%