third_party/optional/tests/observers.cpp

#include "catch.hpp"
#include "optional.hpp"

struct move_detector {
  move_detector() = default;
  move_detector(move_detector &&rhs) { rhs.been_moved = true; }
  bool been_moved = false;
};

TEST_CASE("Observers", "[observers]") {
  tl::optional<int> o1 = 42;
  tl::optional<int> o2;
  const tl::optional<int> o3 = 42;

  REQUIRE(*o1 == 42);
  REQUIRE(*o1 == o1.value());
  REQUIRE(o2.value_or(42) == 42);
  REQUIRE(o3.value() == 42);
  auto success = std::is_same<decltype(o1.value()), int &>::value;
  REQUIRE(success);
  success = std::is_same<decltype(o3.value()), const int &>::value;
  REQUIRE(success);
  success = std::is_same<decltype(std::move(o1).value()), int &&>::value;
  REQUIRE(success);

  #ifndef TL_OPTIONAL_NO_CONSTRR
  success = std::is_same<decltype(std::move(o3).value()), const int &&>::value;
  REQUIRE(success);
  #endif

  tl::optional<move_detector> o4{tl::in_place};
  move_detector o5 = std::move(o4).value();
  REQUIRE(o4->been_moved);
  REQUIRE(!o5.been_moved);
}