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Make uniform_floating_point_distribution reproducible

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By moving to use our `uniform_integer_distribution`, which is
reproducible across different platforms, instead of the stdlib
one which is not, we can provide reproducible results for `float`s
and `double`s. Still no reproducibility for `long double`s, because
those are too different across different platforms.
This commit is contained in:
Martin Hořeňovský 2023-12-10 12:10:19 +01:00
parent ed9d672b5c
commit 28c66fdc5a
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GPG Key ID: DE48307B8B0D381A
2 changed files with 81 additions and 3 deletions
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5
src/catch2/internal/catch_uniform_floating_point_distribution.hpp
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@ -10,10 +10,10 @@
#define CATCH_UNIFORM_FLOATING_POINT_DISTRIBUTION_HPP_INCLUDED
#include <catch2/internal/catch_random_floating_point_helpers.hpp>
#include <catch2/internal/catch_uniform_integer_distribution.hpp>
#include <cmath>
#include <type_traits>
#include <random>
namespace Catch {
@ -76,8 +76,7 @@ class uniform_floating_point_distribution {
FloatType m_a, m_b;
FloatType m_ulp_magnitude;
WidthType m_floats_in_range;
// TODO: we want to eventually replace this distribution with our own for reproducibility
std::uniform_int_distribution<WidthType> m_int_dist;
uniform_integer_distribution<WidthType> m_int_dist;
// In specific cases, we can overflow into `inf` when computing the
// `steps * g` offset. To avoid this, we don't offset by more than this

79
tests/SelfTest/IntrospectiveTests/RandomNumberGeneration.tests.cpp
View File

@ -16,6 +16,8 @@
#include <catch2/generators/catch_generators.hpp>
#include <catch2/matchers/catch_matchers_range_equals.hpp>
#include <random>
TEST_CASE("Our PCG implementation provides expected results for known seeds", "[rng]") {
Catch::SimplePcg32 rng;
SECTION("Default seeded") {
@ -489,3 +491,80 @@ TEMPLATE_TEST_CASE( "uniform_integer_distribution is reproducible",
REQUIRE_THAT(generated, Catch::Matchers::RangeEquals(uniform_integer_test_params<TestType>::expected));
}
namespace {
template <typename T>
struct uniform_fp_test_params;
template<>
struct uniform_fp_test_params<float> {
// These are exactly representable
static constexpr float lowest = -256.125f;
static constexpr float highest = 385.125f;
// These are just round-trip formatted
static constexpr float expected[] = { 92.56961f,
-23.170044f,
310.81833f,
-53.023132f,
105.03287f,
198.77591f,
-172.72931f,
51.805176f,
-241.10156f,
64.66101f,
212.12509f,
-49.24292f,
-177.1399f,
245.23679f,
173.22421f };
};
template <>
struct uniform_fp_test_params<double> {
// These are exactly representable
static constexpr double lowest = -234582.9921875;
static constexpr double highest = 261238.015625;
// These are just round-trip formatted
static constexpr double expected[] = { 35031.207052832615,
203783.3401838024,
44667.940405848756,
-170100.5877224467,
-222966.7418051684,
127472.72630072923,
-173510.88209096913,
97394.16172239158,
119123.6921592663,
22595.741022785165,
8988.68409120926,
136906.86520606978,
33369.19104222473,
60912.7615841752,
-149060.05936760217 };
};
// We need these definitions for C++14 and earlier, but
// GCC will complain about them in newer C++ standards
#if __cplusplus <= 201402L
constexpr float uniform_fp_test_params<float>::expected[];
constexpr double uniform_fp_test_params<double>::expected[];
#endif
} // namespace
TEMPLATE_TEST_CASE( "uniform_floating_point_distribution is reproducible",
"[rng][distribution][floating-point][approvals]",
float,
double ) {
Catch::SimplePcg32 pcg( 0xaabb'aabb );
const auto lowest = uniform_fp_test_params<TestType>::lowest;
const auto highest = uniform_fp_test_params<TestType>::highest;
Catch::uniform_floating_point_distribution<TestType> dist( lowest, highest );
constexpr auto iters = 15;
std::array<TestType, iters> generated;
for ( int i = 0; i < iters; ++i ) {
generated[i] = dist( pcg );
}
REQUIRE_THAT( generated, Catch::Matchers::RangeEquals( uniform_fp_test_params<TestType>::expected ) );
}