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<?php
namespace Faker\Test\Provider;
use Faker\Provider\Biased;
use Faker\Test\TestCase;
/**
* @group legacy
*/
final class BiasedTest extends TestCase
{
public const MAX = 10;
public const NUMBERS = 25000;
protected $results = [];
protected function setUp(): void
{
parent::setUp();
$this->results = array_fill(1, self::MAX, 0);
}
public function performFake($function)
{
for ($i = 0; $i < self::NUMBERS; ++$i) {
++$this->results[$this->faker->biasedNumberBetween(1, self::MAX, $function)];
}
}
public function testUnbiased()
{
$this->performFake(['\Faker\Provider\Biased', 'unbiased']);
// assert that all numbers are near the expected unbiased value
foreach ($this->results as $number => $amount) {
// integral
$assumed = (1 / self::MAX * $number) - (1 / self::MAX * ($number - 1));
// calculate the fraction of the whole area
$assumed /= 1;
self::assertGreaterThan(self::NUMBERS * $assumed * .95, $amount, 'Value was more than 5 percent under the expected value');
self::assertLessThan(self::NUMBERS * $assumed * 1.05, $amount, 'Value was more than 5 percent over the expected value');
}
}
public function testLinearHigh()
{
$this->performFake(['\Faker\Provider\Biased', 'linearHigh']);
foreach ($this->results as $number => $amount) {
// integral
$assumed = 0.5 * (1 / self::MAX * $number) ** 2 - 0.5 * (1 / self::MAX * ($number - 1)) ** 2;
// calculate the fraction of the whole area
$assumed /= 1 ** 2 * .5;
self::assertGreaterThan(self::NUMBERS * $assumed * .9, $amount, 'Value was more than 10 percent under the expected value');
self::assertLessThan(self::NUMBERS * $assumed * 1.1, $amount, 'Value was more than 10 percent over the expected value');
}
}
public function testLinearLow()
{
$this->performFake(['\Faker\Provider\Biased', 'linearLow']);
foreach ($this->results as $number => $amount) {
// integral
$assumed = -0.5 * (1 / self::MAX * $number) ** 2 - -0.5 * (1 / self::MAX * ($number - 1)) ** 2;
// shift the graph up
$assumed += 1 / self::MAX;
// calculate the fraction of the whole area
$assumed /= 1 ** 2 * .5;
self::assertGreaterThan(self::NUMBERS * $assumed * .9, $amount, 'Value was more than 10 percent under the expected value');
self::assertLessThan(self::NUMBERS * $assumed * 1.1, $amount, 'Value was more than 10 percent over the expected value');
}
}
protected function getProviders(): iterable
{
yield new Biased($this->faker);
}
}
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