lix/tests/unit/libutil/json-utils.cc
eldritch horrors c208e918e5 fix: nlohmann::adl_serializer for std::optional (#9147)
This allows templates such as `NLOHMANN_DEFINE_TYPE_*` templates and other generators with things like `std::vector<std::optional<T>>`.

Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
(cherry picked from commit 02bd821f2e71372d31bbe6700bd68086cc2ee70a)
Change-Id: I8b0ebcf2af4226610dadd565962f2d2327415a03
2024-03-04 07:11:25 +01:00

58 lines
1.6 KiB
C++

#include <vector>
#include <optional>
#include <gtest/gtest.h>
#include "json-utils.hh"
namespace nix {
/* Test `to_json` and `from_json` with `std::optional` types.
* We are specifically interested in whether we can _nest_ optionals in STL
* containers so we that we can leverage existing adl_serializer templates. */
TEST(to_json, optionalInt) {
std::optional<int> val = std::make_optional(420);
ASSERT_EQ(nlohmann::json(val), nlohmann::json(420));
val = std::nullopt;
ASSERT_EQ(nlohmann::json(val), nlohmann::json(nullptr));
}
TEST(to_json, vectorOfOptionalInts) {
std::vector<std::optional<int>> vals = {
std::make_optional(420),
std::nullopt,
};
ASSERT_EQ(nlohmann::json(vals), nlohmann::json::parse("[420,null]"));
}
TEST(to_json, optionalVectorOfInts) {
std::optional<std::vector<int>> val = std::make_optional(std::vector<int> {
-420,
420,
});
ASSERT_EQ(nlohmann::json(val), nlohmann::json::parse("[-420,420]"));
val = std::nullopt;
ASSERT_EQ(nlohmann::json(val), nlohmann::json(nullptr));
}
TEST(from_json, optionalInt) {
nlohmann::json json = 420;
std::optional<int> val = json;
ASSERT_TRUE(val.has_value());
ASSERT_EQ(*val, 420);
json = nullptr;
json.get_to(val);
ASSERT_FALSE(val.has_value());
}
TEST(from_json, vectorOfOptionalInts) {
nlohmann::json json = { 420, nullptr };
std::vector<std::optional<int>> vals = json;
ASSERT_EQ(vals.size(), 2);
ASSERT_TRUE(vals.at(0).has_value());
ASSERT_EQ(*vals.at(0), 420);
ASSERT_FALSE(vals.at(1).has_value());
}
} /* namespace nix */