public function concatMapTo_Then_Complete_Task()
{
$xs = Observable::fromArray([4, 3, 2, 1]);
$ys = Observable::just(42);
$results = [];
$completed = false;
$xs->concatMapTo($ys)->subscribeCallback(function ($x) use(&$results) {
$results[] = $x;
}, function ($e) {
$this->fail();
}, function () use(&$completed) {
$completed = true;
});
$this->assertTrue($completed);
$this->assertEquals([42, 42, 42, 42], $results);
}