<?php
class DieHardTest extends PHPUnit_Framework_TestCase
{
/**
* Birthday spacings: Choose random points on a large interval.
* The spacings between the points should be asymptotically exponentially
* distributed.
*/
public function testBirthday()
{
// Number of buckets to make
$num_buckets = 17;
// How much tolerance should we allow? 0.01 = 1% 0.50 = 50%, etc.
$tolerance = 0.03;
$rand_min = 200000;
$rand_max = 600000;
$rand_step = 100000;
$minT = (1.00 - $tolerance);
$maxT = (1.00 + $tolerance);
for ($nums_to_generate = $rand_min; $nums_to_generate < $rand_max; $nums_to_generate += $rand_step) {
$buckets = array_fill(0, $num_buckets, 0);
// The number of ints we expect per bucket +/- 2%;
$min = (int) ceil($minT * $nums_to_generate / $num_buckets);
$max = (int) floor($maxT * $nums_to_generate / $num_buckets);
for ($i = 0; $i < $nums_to_generate; ++$i) {
$random = random_int(0, 999);
$bucket = $random % $num_buckets;
$buckets[$bucket]++;
}
for ($i = 0; $i < $num_buckets; ++$i) {
// Debugging code:
if ($buckets[$i] <= $min ) {
var_dump([
'bucket' => $i,
'value' => $buckets[$i],
'min' => $min,
'nums' => $nums_to_generate,
'reason' => 'below min'
]);
}
if ($buckets[$i] >= $max ) {
var_dump([
'bucket' => $i,
'value' => $buckets[$i],
'maax' => $max,
'nums' => $nums_to_generate,
'reason' => 'above max'
]);
}
$this->assertTrue($buckets[$i] < $max && $buckets[$i] > $min);
}
}
}
}
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