gd-tools/Catch2-3.5.2/examples/310-Gen-VariablesInGenerators.cpp

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// Copyright Catch2 Authors
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.txt or copy at
// https://www.boost.org/LICENSE_1_0.txt)
// SPDX-License-Identifier: BSL-1.0
// 310-Gen-VariablesInGenerator.cpp
// Shows how to use variables when creating generators.
// Note that using variables inside generators is dangerous and should
// be done only if you know what you are doing, because the generators
// _WILL_ outlive the variables -- thus they should be either captured
// by value directly, or copied by the generators during construction.
#include <catch2/catch_test_macros.hpp>
#include <catch2/generators/catch_generators_adapters.hpp>
#include <catch2/generators/catch_generators_random.hpp>
TEST_CASE("Generate random doubles across different ranges",
"[generator][example][advanced]") {
// Workaround for old libstdc++
using record = std::tuple<double, double>;
// Set up 3 ranges to generate numbers from
auto r = GENERATE(table<double, double>({
record{3, 4},
record{-4, -3},
record{10, 1000}
}));
// This will not compile (intentionally), because it accesses a variable
// auto number = GENERATE(take(50, random(std::get<0>(r), std::get<1>(r))));
// GENERATE_COPY copies all variables mentioned inside the expression
// thus this will work.
auto number = GENERATE_COPY(take(50, random(std::get<0>(r), std::get<1>(r))));
REQUIRE(std::abs(number) > 0);
}
// Compiling and running this file will result in 150 successful assertions