public function testGroupJoinToSelfWithInnerIndexBy(\Pinq\ITraversable $traversable)
{
$traversable = $traversable->indexBy(function ($i) {
return $i - 1;
});
$traversable = $traversable->groupJoin($traversable)->on(function ($outer, $inner) {
return $outer > $inner;
})->to(function ($outer, \Pinq\ITraversable $group) {
return $outer . ':' . $group->implode(',');
});
$this->assertMatches($traversable, [0 => '1:', 1 => '2:1', 2 => '3:1,2', 3 => '4:1,2,3', 4 => '5:1,2,3,4', 5 => '6:1,2,3,4,5', 6 => '7:1,2,3,4,5,6', 7 => '8:1,2,3,4,5,6,7', 8 => '9:1,2,3,4,5,6,7,8', 9 => '10:1,2,3,4,5,6,7,8,9']);
}