public function test_suffle()
{
$this->assert_values_same([], cs_iter([])->shuffle());
$this->assert_values_same([9], cs_iter([9])->shuffle());
// Let grab a list of 12 elements, the number of
// its unique permutations is d = 12! ≈ 5*10^8.
$list = cs_iter([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
// If we do n = 100 random draws from a set of all
// permutations, the probability of a collision
// p(n, d) ≈ 1 - exp(-n(n-1)/2d) ≈ 0.00001 [1]
//
// [1]: Search for the generalized birthday problem.
$n = 100;
$draws = cs_set();
for ($i = 0; $i < $n; ++$i) {
$draw = $list->shuffle()->to_array();
$draws->add(implode(',', $draw));
}
$this->assertEqual($n, $draws->count());
}
function testNullSupport()
{
$set = cs_set();
$this->assertFalse($set->contains(null));
$set->add(null);
$this->assertTrue($set->contains(null));
$this->assertFalse($set->contains(false));
$this->assertFalse($set->contains(0));
$set->remove(null);
$this->assertFalse($set->contains(null));
}
