public function concatMapTo_Then_Error_Task()
{
$xs = Observable::fromArray([4, 3, 2, 1]);
$ys = Observable::error(new \Exception("test"));
$results = [];
$completed = false;
$error = false;
$xs->concatMapTo($ys)->subscribeCallback(function ($x) use(&$results) {
$results[] = $x;
}, function (\Exception $e) use(&$results, &$error) {
$error = true;
$this->assertSame("test", $e->getMessage());
}, function () use(&$completed) {
$completed = true;
});
$this->assertFalse($completed);
$this->assertTrue($error);
}