mp-units/test/unit_test/runtime/magnitude_test.cpp

// The MIT License (MIT)
//
// Copyright (c) 2018 Mateusz Pusz
//
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// of this software and associated documentation files (the "Software"), to deal
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// SOFTWARE.

#include <units/magnitude.h>
#include <units/ratio.h>
#include <catch2/catch.hpp>
#include <type_traits>

namespace units::mag
{

TEST_CASE("make_ratio performs prime factorization correctly")
{
  SECTION("Performs prime factorization when denominator is 1")
  {
    CHECK(make_ratio<1>() == magnitude<>{});
    CHECK(make_ratio<2>() == magnitude<base_power{2}>{});
    CHECK(make_ratio<3>() == magnitude<base_power{3}>{});
    CHECK(make_ratio<4>() == magnitude<base_power{2, 2}>{});

    CHECK(make_ratio<792>() == magnitude<base_power{2, 3}, base_power{3, 2}, base_power{11}>{});
  }

  SECTION("Reduces fractions to lowest terms")
  {
    CHECK(make_ratio<8, 8>() == magnitude<>{});
    CHECK(make_ratio<50, 80>() == magnitude<base_power{2, -3}, base_power{5}>{});
  }
}

TEST_CASE("Equality works for magnitudes")
{
  SECTION("Equivalent ratios are equal")
  {
    CHECK(make_ratio<1>() == make_ratio<1>());
    CHECK(make_ratio<3>() == make_ratio<3>());
    CHECK(make_ratio<3, 4>() == make_ratio<9, 12>());
  }

  SECTION("Different ratios are unequal")
  {
    CHECK(make_ratio<3>() != make_ratio<5>());
    CHECK(make_ratio<3>() != make_ratio<3, 2>());
  }

  SECTION("Supports constexpr")
  {
    constexpr auto eq = (make_ratio<4, 5>() == make_ratio<4, 3>());
    CHECK(!eq);
  }
}

TEST_CASE("Multiplication works for magnitudes")
{
  SECTION("Reciprocals reduce to null magnitude")
  {
    CHECK(make_ratio<3, 4>() * make_ratio<4, 3>() == make_ratio<1>());
  }

  SECTION("Products work as expected")
  {
    CHECK(make_ratio<4, 5>() * make_ratio<4, 3>() == make_ratio<16, 15>());
  }

  SECTION("Products handle pi correctly")
  {
     CHECK(
         pi_to_the<1>() * make_ratio<2, 3>() * pi_to_the<ratio{-1, 2}>() ==
         magnitude<base_power{2}, base_power{3, -1}, base_power<pi_base>{ratio{1, 2}}>{});
  }

  SECTION("Supports constexpr")
  {
    constexpr auto p = make_ratio<4, 5>() * make_ratio<4, 3>();
    CHECK(p == make_ratio<16, 15>());
  }
}

TEST_CASE("Division works for magnitudes")
{
  SECTION("Dividing anything by itself reduces to null magnitude")
  {
    CHECK(make_ratio<3, 4>() / make_ratio<3, 4>() == make_ratio<1>());
    CHECK(make_ratio<15>() / make_ratio<15>() == make_ratio<1>());
  }

  SECTION("Quotients work as expected")
  {
    CHECK(make_ratio<4, 5>() / make_ratio<4, 3>() == make_ratio<3, 5>());
  }

  SECTION("Supports constexpr")
  {
    constexpr auto q = make_ratio<4, 5>() / make_ratio<4, 3>();
    CHECK(q == make_ratio<3, 5>());
  }
}

namespace detail
{

TEST_CASE("Prime factorization")
{
  SECTION ("1 factors into the null magnitude")
  {
    CHECK(prime_factorization_v<1> == magnitude<>{});
  }

  SECTION ("Prime numbers factor into themselves")
  {
    CHECK(prime_factorization_v<2> == magnitude<base_power{2}>{});
    CHECK(prime_factorization_v<3> == magnitude<base_power{3}>{});
    CHECK(prime_factorization_v<5> == magnitude<base_power{5}>{});
    CHECK(prime_factorization_v<7> == magnitude<base_power{7}>{});
    CHECK(prime_factorization_v<11> == magnitude<base_power{11}>{});

    CHECK(prime_factorization_v<41> == magnitude<base_power{41}>{});
  }

  SECTION("Prime factorization finds factors and multiplicities")
  {
    CHECK(prime_factorization_v<792> ==
          magnitude<base_power{2, 3}, base_power{3, 2}, base_power{11}>{});
  }
}

TEST_CASE("is_prime detects primes")
{
  SECTION("Non-positive numbers are not prime")
  {
    CHECK(!is_prime(-1328));
    CHECK(!is_prime(-1));
    CHECK(!is_prime(0));
  }

  SECTION("1 is not prime")
  {
    CHECK(!is_prime(1));
  }

  SECTION("Discriminates between primes and non-primes")
  {
    CHECK(is_prime(2));
    CHECK(is_prime(3));
    CHECK(!is_prime(4));
    CHECK(is_prime(5));
    CHECK(!is_prime(6));
    CHECK(is_prime(7));
    CHECK(!is_prime(8));
    CHECK(!is_prime(9));

    CHECK(is_prime(7919));
  }
}

TEST_CASE("pairwise_all evaluates all pairs")
{
  SECTION("always true for empty tuples")
  {
    CHECK(pairwise_all{[](auto, auto){ return true; }}());
    CHECK(pairwise_all{[](auto, auto){ return false; }}());
  }

  SECTION("always true for single-element tuples")
  {
    CHECK(pairwise_all{[](auto, auto){ return true; }}(1));
    CHECK(pairwise_all{[](auto, auto){ return false; }}(3.14));
    CHECK(pairwise_all{[](auto, auto){ return true; }}('x'));
  }

  SECTION("true for longer tuples iff true for all neighbouring pairs")
  {
    CHECK(pairwise_all{std::less{}}(1, 1.5));
    CHECK(pairwise_all{std::less{}}(1, 1.5, 2));
    CHECK(!pairwise_all{std::less{}}(1, 2.0, 2));
    CHECK(!pairwise_all{std::less{}}(1, 2.5, 2));
  }
}

TEST_CASE("strictly_increasing")
{
  SECTION ("Empty input is sorted")
  {
    CHECK(strictly_increasing());
  }

  SECTION ("Single-element input is sorted")
  {
    CHECK(strictly_increasing(3));
    CHECK(strictly_increasing(15.42));
    CHECK(strictly_increasing('c'));
  }

  SECTION ("Multi-value inputs compare correctly")
  {
    CHECK(strictly_increasing(3, 3.14));
    CHECK(!strictly_increasing(3, 3.0));
    CHECK(!strictly_increasing(4, 3.0));
  }
}

} // namespace detail

} // namespace units::mag