sots-engine/tests/app/test_trade_raid.cpp

// The trade-raid block is the strategic turn's dominant generator cost, so its WORD COUNT is
// load-bearing in a way its decisions are not. These tests pin the count, the two no-draw
// early-outs of the chance helper, and the roll order -- all against a scripted generator, so
// nothing here depends on the real MT19937.
#include <cstdio>
#include <vector>

#include "app/trade_raid.h"
#include "mars/rng/mt19937.h"

static int failures = 0;
#define CHECK(c)                                                     \
    do {                                                             \
        if (!(c)) {                                                  \
            std::printf("FAIL %s:%d  %s\n", __FILE__, __LINE__, #c); \
            ++failures;                                              \
        }                                                            \
    } while (0)

namespace {

// A generator that hands out a scripted sequence and counts what it handed out.
class Scripted final : public sots::sim::IRandom {
public:
    explicit Scripted(std::vector<float> f) : f_(std::move(f)) {}
    float NextFloat() override {
        ++draws;
        return f_.empty() ? 0.f : f_[(cursor_++) % f_.size()];
    }
    std::uint32_t NextIntInclusive(std::uint32_t) override {
        ++draws;
        return 0;
    }
    std::uint32_t NextUInt32() override {
        ++draws;
        return 0;
    }
    int draws = 0;

private:
    std::vector<float> f_;
    std::size_t cursor_ = 0;
};

}  // namespace

int main() {
    using namespace sots::app;

    // --- the chance helper's two no-draw early-outs ------------------------------------
    {
        Scripted g({0.5f});
        CHECK(Chance(g, 0.f) == false);
        CHECK(Chance(g, -1.f) == false);
        CHECK(Chance(g, 1.f) == true);
        CHECK(Chance(g, 2.f) == true);
        CHECK(g.draws == 0);  // four calls, zero words: both early-outs return before drawing
    }
    // --- the comparison is `p > r`, so equality FAILS and still costs a word -----------
    {
        Scripted g({0.25f, 0.25f});
        CHECK(Chance(g, 0.25f) == false);  // p == r -> false
        CHECK(g.draws == 1);
        CHECK(Chance(g, 0.5f) == true);  // p > r -> true
        CHECK(g.draws == 2);
    }
    // --- the word count is two per player when the NPC gate is open -------------------
    {
        Scripted g({0.9f});  // every roll fails; the count must not depend on that
        const TradeRaidResult r = RollTradeRaids(g, 8, TradeRaidOdds{}, TradeRaidGates{});
        CHECK(r.players == 8);
        CHECK(r.words == 16);
        CHECK(g.draws == 16);
        CHECK(r.playerRaidHits == 0);
        CHECK(r.npcRaidHits == 0);
        CHECK(r.refugeeRaidHits == 0);
    }
    // --- ... and the count is unchanged when every roll succeeds -----------------------
    {
        Scripted g({0.0f});  // every roll succeeds (p > 0)
        const TradeRaidResult r = RollTradeRaids(g, 8, TradeRaidOdds{}, TradeRaidGates{});
        CHECK(r.words == 16);
        CHECK(r.playerRaidHits == 8);
        CHECK(r.npcRaidHits == 8);
    }
    // --- one per player when the NPC gate is shut, three when the refugee one is open --
    {
        Scripted g({0.9f});
        TradeRaidGates gates;
        gates.npcRaids = false;
        CHECK(RollTradeRaids(g, 7, TradeRaidOdds{}, gates).words == 7);
        gates.npcRaids = true;
        gates.refugeeRaids = true;
        Scripted g2({0.9f});
        CHECK(RollTradeRaids(g2, 7, TradeRaidOdds{}, gates).words == 21);
    }
    // --- a degenerate player vector costs nothing --------------------------------------
    {
        Scripted g({0.9f});
        CHECK(RollTradeRaids(g, 0, TradeRaidOdds{}, TradeRaidGates{}).words == 0);
        CHECK(RollTradeRaids(g, -3, TradeRaidOdds{}, TradeRaidGates{}).words == 0);
        CHECK(g.draws == 0);
    }
    // --- odds pinned at 0 or 1 cost NOTHING, and the counter says so -------------------
    // This is the case that would silently break a count-the-calls implementation: a tuning
    // table that pushes an odds value out of (0, 1) removes the draw, not just the outcome.
    {
        Scripted g({0.9f});
        TradeRaidOdds odds;
        odds.player = 0.f;
        odds.npc = 1.f;
        const TradeRaidResult r = RollTradeRaids(g, 8, odds, TradeRaidGates{});
        CHECK(r.words == 0);
        CHECK(g.draws == 0);
        CHECK(r.playerRaidHits == 0);
        CHECK(r.npcRaidHits == 8);
    }
    // --- against the real generator: 16 words is 16 words -----------------------------
    {
        mars::rng::MT19937 gen(12345u);
        class Adapt final : public sots::sim::IRandom {
        public:
            explicit Adapt(mars::rng::MT19937& g) : g_(g) {}
            float NextFloat() override { return g_.next_float(); }
            std::uint32_t NextIntInclusive(std::uint32_t n) override {
                return g_.next_int_inclusive(n);
            }
            std::uint32_t NextUInt32() override { return g_.next_u32(); }

        private:
            mars::rng::MT19937& g_;
        } a(gen);
        const int before = gen.index();
        const TradeRaidResult r = RollTradeRaids(a, 8, TradeRaidOdds{}, TradeRaidGates{});
        CHECK(r.words == 16);
        CHECK(gen.index() - before == 16);
    }

    std::printf(failures ? "trade_raid: FAILED (%d)\n" : "trade_raid: ok (%d failures)\n",
                failures);
    return failures ? 1 : 0;
}