e5bf2aa055
CMakeLists.txt: - Native host build by default; Emscripten-target detection plumbed but WASM emit deferred to stream 7 (playground build script). - Header-only INTERFACE library `nisps_core`. - Host test executable `nisps_core_tests` compiled with -Wall -Wextra -Werror -Wpedantic (Chris's rules: clean build is non-negotiable). tests/cpp/test_helpers.hpp: - Minimal NISPS_TEST / NISPS_EXPECT / NISPS_EXPECT_NEAR macros, no external deps. Rationale documented in-file: Catch2/doctest would add ~10MB and 30s for what is currently <100 LOC of test runtime. 22 unit tests covering FixedBuffer (5), RingBuffer (5), Rng (7), math (5). All green; verified via `cmake --build nisps/build && ./nisps/build/nisps_core_tests`.
78 lines
2.2 KiB
C++
78 lines
2.2 KiB
C++
// tests/cpp/test_rng.cpp — verify deterministic seeding, range bounds, and
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// reasonable statistical shape on the gaussian helper.
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#include "test_helpers.hpp"
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#include "../../nisps/core/rng.hpp"
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NISPS_TEST(rng_deterministic_for_same_seed) {
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nisps::Rng a(42ull);
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nisps::Rng b(42ull);
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for (int i = 0; i < 1000; ++i) {
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NISPS_EXPECT(a.next_u64() == b.next_u64());
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}
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}
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NISPS_TEST(rng_diverges_for_different_seeds) {
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nisps::Rng a(0ull);
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nisps::Rng b(1ull);
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int distinct = 0;
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for (int i = 0; i < 100; ++i) {
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if (a.next_u64() != b.next_u64()) ++distinct;
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}
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// Should differ in nearly every draw (probability of collision ~ 2^-64).
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NISPS_EXPECT(distinct >= 99);
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}
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NISPS_TEST(rng_zero_seed_does_not_lock_up) {
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nisps::Rng r(0ull);
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// Pure xoshiro with all-zero state is degenerate; our splitmix64 fan-out
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// should prevent that. Confirm we get nonzero output.
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bool any_nonzero = false;
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for (int i = 0; i < 16; ++i) {
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if (r.next_u64() != 0ull) { any_nonzero = true; break; }
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}
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NISPS_EXPECT(any_nonzero);
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}
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NISPS_TEST(rng_uniform_in_unit_interval) {
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nisps::Rng r(7ull);
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for (int i = 0; i < 10000; ++i) {
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const float v = r.next_float_uniform();
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NISPS_EXPECT(v >= 0.f);
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NISPS_EXPECT(v < 1.f);
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}
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}
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NISPS_TEST(rng_signed_in_minus_plus) {
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nisps::Rng r(7ull);
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for (int i = 0; i < 10000; ++i) {
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const float v = r.next_float_signed();
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NISPS_EXPECT(v >= -1.f);
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NISPS_EXPECT(v < 1.f);
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}
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}
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NISPS_TEST(rng_uniform_mean_near_half) {
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nisps::Rng r(123ull);
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double sum = 0.0;
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constexpr int N = 100000;
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for (int i = 0; i < N; ++i) sum += r.next_float_uniform();
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const double mean = sum / N;
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NISPS_EXPECT_NEAR(mean, 0.5, 0.01);
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}
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NISPS_TEST(rng_gaussian_stddev_close_to_one) {
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nisps::Rng r(99ull);
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constexpr int N = 100000;
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double sum = 0.0, sq = 0.0;
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for (int i = 0; i < N; ++i) {
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const double v = r.next_float_gaussian(1.f);
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sum += v;
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sq += v * v;
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}
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const double mean = sum / N;
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const double var = sq / N - mean * mean;
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NISPS_EXPECT_NEAR(mean, 0.0, 0.05);
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// sum-of-three-uniforms gives variance exactly 1.0 in the limit.
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NISPS_EXPECT_NEAR(var, 1.0, 0.05);
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}
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