tests/test_fixed_point.cpp


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#include <catch2/catch_test_macros.hpp>
#include "fixed_point.h"

TEST_CASE("fp_t addition is commutative") {
    fp_t a = fp_t::from_int(1);
    fp_t b = fp_t::from_int(2);
    CHECK(a + b == b + a);
    REQUIRE(a.raw != 0);
}

TEST_CASE("fp_t subtraction anti-commutative") {
    fp_t a = fp_t::from_int(3);
    fp_t b = fp_t::from_int(2);
    fp_t c = fp_t::from_int(1);
    fp_t d = fp_t::from_int(-1);
    CHECK((a - b == c && b - a == d));
    REQUIRE(a.raw != 0);
}

TEST_CASE("fp_t multiplication is commutative") {
    fp_t a = fp_t::from_int(2);
    fp_t b = fp_t::from_int(5);
    CHECK(a * b == b * a);
    REQUIRE(a.raw != 1);
}

TEST_CASE("fp_t addition overflows") {
    fp_t a = fp_t::from_raw(INT32_MAX);
    fp_t b = fp_t::from_raw(1);
    fp_t c = fp_t::from_raw(INT32_MIN);
    CHECK(a + b == c);
}

TEST_CASE("fp_t subtraction underflows") {
    fp_t a = fp_t::from_raw(INT32_MIN);
    fp_t b = fp_t::from_raw(1);
    fp_t c = fp_t::from_raw(INT32_MAX);
    CHECK(a - b == c);
}

TEST_CASE("fp_t multiplication overflows") {
    fp_t a = fp_t::from_raw(INT32_MAX);
    fp_t b = fp_t::from_int(2);
    fp_t c = fp_t::from_raw(-2);
    CHECK(a * b == c);
}

TEST_CASE("fp_t multiplication drops percision under 1 ULP") {
    fp_t a = fp_t::from_raw(1);
    fp_t b = fp_t::from_raw(0);
    CHECK(a * a == b);
}