Eris is a porting of QuickCheck and property-based testing tools to the PHP and PHPUnit ecosystem.

In property-based testing, several properties that the System Under Test must respect are defined, and a large sample of generated inputs is sent to it in an attempt to break the properties.

You can install Eris through Composer by adding:

    "require": {
        "giorgiosironi/eris": "dev-master"
    }

to your composer.json, and run composer install.

You can run some of Eris example tests with vendor/bin/phpunit vendor/giorgiosironi/eris/examples.

Here is an empty sample project installing Eris.

Please note the project is in alpha stage and the API may change at any time.

This test tries to verify that all natural numbers are greater than 42. It's a failing test designed to show you an example of error message.

<?php
use Eris\Generator;

class ReadmeTest extends \PHPUnit_Framework_TestCase
{
    use Eris\TestTrait;

    public function testNaturalNumbersMagnitude()
    {
        $this->forAll(
            Generator\nat(1000)
        )
            ->then(function($number) {
                $this->assertTrue(
                    $number < 42,
                    "$number is not less than 42 apparently"
                );
            });
    }
}

Eris generates a sample of elements from the required domain (here the integers from 0 to plus infinity) and verifies a property on each of them, stopping at the first failure.

[10:34:32][giorgio@Bipbip:~/code/eris]$ vendor/bin/phpunit examples/ReadmeTest.php
PHPUnit 4.3.5 by Sebastian Bergmann.

Configuration read from /home/giorgio/code/eris/phpunit.xml

F

Time: 234 ms, Memory: 3.25Mb

There was 1 failure:

1) ReadmeTest::testNaturalNumbersMagnitude
42 is not less than 42 apparently
Failed asserting that false is true.

/home/giorgio/code/eris/examples/ReadmeTest.php:15
/home/giorgio/code/eris/src/Eris/Quantifier/Evaluation.php:48
/home/giorgio/code/eris/src/Eris/Quantifier/RoundRobinShrinking.php:45
/home/giorgio/code/eris/src/Eris/Quantifier/ForAll.php:69
/home/giorgio/code/eris/src/Eris/Quantifier/Evaluation.php:50
/home/giorgio/code/eris/src/Eris/Quantifier/ForAll.php:71
/home/giorgio/code/eris/src/Eris/Quantifier/ForAll.php:87
/home/giorgio/code/eris/examples/ReadmeTest.php:16
/home/giorgio/code/eris/examples/ReadmeTest.php:16

FAILURES!
Tests: 1, Assertions: 826, Failures: 1.

Eris also tries to shrink the input after a failure, giving you the simplest input that still fails the test. In this example, the original input was probably something like 562, but Eris tries to make it smaller until the test became green again. The smallest value that still fails the test is the one presented to you.

Consult the ChangeLog file to know the latest new features.

Feel free to open issues on the GitHub project for support.