GroupBy + Take Results in Incorrect Return Sequence #249
Description
Given the following:
#include "rxcpp/rx.hpp"
namespace rx=rxcpp;
int main()
{
rx::observable<>::range(0, 10)
.group_by([](auto i) { return 0; }, [](auto i) { return i; })
.take(1)
.subscribe([](auto g) {
auto key = g.get_key();
std::cout << "On Next: " << key << std::endl;
g.subscribe([key](auto i) { std::cout << "Group=" << key << " Value=" << i << std::endl; }, [key]() { std::cout << "Group=" << key << " completed" << std::endl; });
}, [](auto err){
std::cout << "Error occured: " << std::endl;
}, []() {
std::cout << "Completed!" << std::endl;
});
return 0;
}I'd expect to see the following output:
On Next: 0
Group=0 Value=0
Group=0 Value=1
Group=0 Value=2
Group=0 Value=3
Group=0 Value=4
Group=0 Value=5
Group=0 Value=6
Group=0 Value=7
Group=0 Value=8
Group=0 Value=9
Group=0 Value=10
Group=0 completed
Completed!
However, I am seeing:
On Next: 0
Completed!
Group=0 Value=0
This is incorrect as it seems to be Take(1)ing on the group's inner sequence instead of the outer observable sequence.
Other implementation's of Rx support the case that this implementation is incorrect. For example, RxJs 4 returns the correct results.
Rx.Observable.range(0, 10)
.groupBy(x => 0, x => x)
.take(1)
.subscribe(x => {
const key = x.key;
x.subscribe(y => console.log('Group' + key + ' Value=' + y), err => console.error(err), () => console.log('Group=' + key + ' completed'));
}, err => console.error(err), () => console.log('Completed!'));returns
"Completed!"
"Group0 Value=0"
"Group0 Value=1"
"Group0 Value=2"
"Group0 Value=3"
"Group0 Value=4"
"Group0 Value=5"
"Group0 Value=6"
"Group0 Value=7"
"Group0 Value=8"
"Group0 Value=9"
"Group=0 completed"