BlackBox

BlackBox is a Property Based Testing framework and test runner.

Property Based Testing is a way to verify a piece of code always behave the same way (aka a Property) by testing it with multiple values of a given type.

The common introduction to this approach is the add function that has 3 properties:

• it is commutative
• it is associative
• it is an identity function

To prove this via BlackBox you can do it this way:

use Innmind\BlackBox\{
    Application,
    Set,
    Runner\Assert,
    Prove,
};

Application::new([])
    ->tryToProve(static function(Prove $prove) {
        yield $prove
            ->proof('add is commutative')
            ->given(
                Set::integers(),
                Set::integers(),
            )
            ->test(static fn(Assert $assert, int $a, int $b) => $assert->same(
                add($a, $b),
                add($b, $a),
            ));

        yield $prove
            ->proof('add is associative')
            ->given(
                Set::integers(),
                Set::integers(),
                Set::integers(),
            )
            ->test(static fn(Assert $assert, int $a, int $b, int $c) => $assert->same(
                add(add($a, $b), $c),
                add($a, add($b, $c)),
            ));

        yield $prove
            ->proof('add is an identity function')
            ->given(Set::integers())
            ->test(static fn(Assert $assert, int $a) => $assert->same(
                $a,
                add($a, 0),
            ));
    })
    ->exit();

By default BlackBox will generate 100 scenarii for each proof.

[!NOTE] BlackBox use the term proof to emphasize that you are testing behaviours not specific scenarii, but these are NOT formal proofs

Installation

composer require --dev innmind/black-box

Documentation

Full documentation can be found in the here.