catch2/projects/SelfTest/UsageTests/ToStringVariant.tests.cpp

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#define CATCH_CONFIG_ENABLE_VARIANT_STRINGMAKER
#include "catch.hpp"
#if defined(CATCH_CONFIG_CPP17_VARIANT)
#include <string>
#include <variant>
TEST_CASE( "variant<std::monostate>", "[toString][variant][approvals]")
{
using type = std::variant<std::monostate>;
CHECK( "{ }" == ::Catch::Detail::stringify(type{}) );
type value {};
CHECK( "{ }" == ::Catch::Detail::stringify(value) );
CHECK( "{ }" == ::Catch::Detail::stringify(std::get<0>(value)) );
}
TEST_CASE( "variant<int>", "[toString][variant][approvals]")
{
using type = std::variant<int>;
CHECK( "0" == ::Catch::Detail::stringify(type{0}) );
}
TEST_CASE( "variant<float, int>", "[toString][variant][approvals]")
{
using type = std::variant<float, int>;
CHECK( "0.5f" == ::Catch::Detail::stringify(type{0.5f}) );
CHECK( "0" == ::Catch::Detail::stringify(type{0}) );
SECTION("valueless by exception") {
struct sample {
operator int() const { throw 42; }
};
type value{1.5f};
REQUIRE_THROWS_AS( value.emplace<int>(sample{}), int );
REQUIRE( value.valueless_by_exception() );
CHECK( "{valueless variant}" == ::Catch::Detail::stringify(value) );
}
}
TEST_CASE( "variant<string, int>", "[toString][variant][approvals]")
{
using type = std::variant<std::string, int>;
CHECK( "\"foo\"" == ::Catch::Detail::stringify(type{"foo"}) );
CHECK( "0" == ::Catch::Detail::stringify(type{0}) );
}
TEST_CASE( "variant<variant<float, int>, string>", "[toString][variant][approvals]")
{
using inner = std::variant<float, int>;
using type = std::variant<inner, std::string>;
CHECK( "0.5f" == ::Catch::Detail::stringify(type{0.5f}) );
CHECK( "0" == ::Catch::Detail::stringify(type{0}) );
CHECK( "\"foo\"" == ::Catch::Detail::stringify(type{"foo"}) );
struct sample {
operator int() const { throw 42; }
};
SECTION("valueless nested variant") {
type value = inner{0.5f};
REQUIRE( std::holds_alternative<inner>(value) );
REQUIRE( std::holds_alternative<float>(std::get<inner>(value)) );
REQUIRE_THROWS_AS( std::get<0>(value).emplace<int>(sample{}), int );
// outer variant is still valid and contains inner
REQUIRE( std::holds_alternative<inner>(value) );
// inner variant is valueless
REQUIRE( std::get<inner>(value).valueless_by_exception() );
CHECK( "{valueless variant}" == ::Catch::Detail::stringify(value) );
}
}
TEST_CASE( "variant<nullptr,int,const char *>", "[toString][variant][approvals]" )
{
using type = std::variant<std::nullptr_t,int,const char *>;
CHECK( "nullptr" == ::Catch::Detail::stringify(type{nullptr}) );
CHECK( "42" == ::Catch::Detail::stringify(type{42}) );
CHECK( "\"Catch me\"" == ::Catch::Detail::stringify(type{"Catch me"}) );
}
#endif // CATCH_INTERNAL_CONFIG_CPP17_VARIANT