cpp-opaque-typedef/opaque_typedef_test.cpp

//
//  opaque_typedef_test.cpp
//  opaque_typedef
//
//  Created by Sam Jaffe on 6/3/18.
//

#include <gmock/gmock.h>
#include <cmath>

#include "opaque_typedef.hpp"

struct degree;
struct radian;

struct degree : types::opaque_typedef<double, struct degree_tag, types::Comparable, types::Convertable<radian>::type> {
  using super::super;
};
struct radian : types::opaque_typedef<double, struct radian_tag, types::Comparable, types::Convertable<degree>::type> {
  using super::super;
};

template<> template <>
types::Convertable<degree>::type<radian::super>::operator degree() const {
  return degree{ self().get() * 90.0 / M_PI_2 };
}

template <> template <>
types::Convertable<radian>::type<degree::super>::operator radian() const {
  return radian{ self().get() * M_PI_2 / 90.0 };
}

void PrintTo(radian const & ot, std::ostream * os) {
  (*os) << double(ot)/M_PI << "π";
}

void PrintTo(degree const & ot, std::ostream * os) {
  (*os) << double(ot) << "°";
}

TEST(OpaqueTypedefTest, Conversion) {
  degree deg{90.0};
  radian rad{M_PI_2};
  
  EXPECT_THAT(radian(deg), rad);
  EXPECT_THAT(degree(rad), deg);
  EXPECT_THAT(radian(double(deg)), ::testing::Not(rad));
  EXPECT_THAT(degree(double(rad)), ::testing::Not(deg));
}

using meters = types::opaque_typedef<double, struct meters_tag, types::Comparable>;
using seconds = types::opaque_typedef<double, struct seconds_tag, types::Comparable>;
using meter_per_second = types::opaque_typedef<double, struct mps_tag, types::Comparable>;

meter_per_second operator/(meters m, seconds s) {
  return meter_per_second{m.get() / s.get()};
}

TEST(OpaqueTypedefTest, MixedFunctions) {
  meters m{10.0};
  seconds s{0.5};

  EXPECT_THAT(m/s, meter_per_second{20.0});
}