maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[libcxx] [test] D26816: Fix non-Standard assumptions when testing sample(). 

sample() isn't specified with a reproducible algorithm, so expecting
exact output is non-Standard. Mark those tests with LIBCPP_ASSERT.

In test_small_population(), we're guaranteed to get all of the elements,
but not necessarily in their original order. When PopulationCategory is
forward, we're guaranteed stability (and can therefore test equal()).
Otherwise, we can only test is_permutation(). (As it happens, both libcxx
and MSVC's STL provide stability in this scenario for input-only iterators.)

llvm-svn: 287383
This commit is contained in:
Stephan T. Lavavej 2016-11-18 21:54:43 +00:00
parent b04c795e24
commit 09c311b9a4
1 changed files with 14 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
libcxx/test/std/algorithms/alg.modifying.operations/alg.random.sample/sample.pass.cpp
View File

@ -19,9 +19,11 @@
#include <algorithm>
#include <random>
#include <type_traits>
#include <cassert>
#include "test_iterators.h"
#include "test_macros.h"
struct ReservoirSampleExpectations {
enum { os = 4 };
@ -60,19 +62,23 @@ void test() {
const unsigned os = Expectations::os;
SampleItem oa[os];
const int *oa1 = Expectations::oa1;
((void)oa1); // Prevent unused warning
const int *oa2 = Expectations::oa2;
((void)oa2); // Prevent unused warning
std::minstd_rand g;
SampleIterator end;
end = std::sample(PopulationIterator(ia),
PopulationIterator(ia + is),
SampleIterator(oa), os, g);
assert(end.base() - oa == std::min(os, is));
assert(std::equal(oa, oa + os, oa1));
// sample() is deterministic but non-reproducible;
// its results can vary between implementations.
LIBCPP_ASSERT(std::equal(oa, oa + os, oa1));
end = std::sample(PopulationIterator(ia),
PopulationIterator(ia + is),
SampleIterator(oa), os, std::move(g));
assert(end.base() - oa == std::min(os, is));
assert(std::equal(oa, oa + os, oa2));
LIBCPP_ASSERT(std::equal(oa, oa + os, oa2));
}
template <template<class...> class PopulationIteratorType, class PopulationItem,
@ -122,7 +128,12 @@ void test_small_population() {
PopulationIterator(ia + is),
SampleIterator(oa), os, g);
assert(end.base() - oa == std::min(os, is));
typedef typename std::iterator_traits<PopulationIterator>::iterator_category PopulationCategory;
if (std::is_base_of<std::forward_iterator_tag, PopulationCategory>::value) {
assert(std::equal(oa, end.base(), oa1));
} else {
assert(std::is_permutation(oa, end.base(), oa1));
}
}
int main() {