forked from catchorg/Catch2
69 lines
2.1 KiB
C++
69 lines
2.1 KiB
C++
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// Copyright Catch2 Authors
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE.txt or copy at
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// https://www.boost.org/LICENSE_1_0.txt)
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// SPDX-License-Identifier: BSL-1.0
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// 301-Gen-MapTypeConversion.cpp
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// Shows how to use map to modify generator's return type.
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// Specifically we wrap a std::string returning generator with a generator
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// that converts the strings using stoi, so the returned type is actually
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// an int.
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#include <catch2/catch_test_macros.hpp>
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#include <catch2/generators/catch_generators_adapters.hpp>
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#include <string>
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#include <sstream>
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namespace {
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// Returns a line from a stream. You could have it e.g. read lines from
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// a file, but to avoid problems with paths in examples, we will use
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// a fixed stringstream.
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class LineGenerator : public Catch::Generators::IGenerator<std::string> {
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std::string m_line;
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std::stringstream m_stream;
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public:
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LineGenerator() {
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m_stream.str("1\n2\n3\n4\n");
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if (!next()) {
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Catch::Generators::Detail::throw_generator_exception("Couldn't read a single line");
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}
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}
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std::string const& get() const override;
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bool next() override {
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return !!std::getline(m_stream, m_line);
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}
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};
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std::string const& LineGenerator::get() const {
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return m_line;
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}
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// This helper function provides a nicer UX when instantiating the generator
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// Notice that it returns an instance of GeneratorWrapper<std::string>, which
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// is a value-wrapper around std::unique_ptr<IGenerator<std::string>>.
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Catch::Generators::GeneratorWrapper<std::string> lines(std::string /* ignored for example */) {
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return Catch::Generators::GeneratorWrapper<std::string>(
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new LineGenerator()
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);
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}
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} // end anonymous namespace
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TEST_CASE("filter can convert types inside the generator expression", "[example][generator]") {
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auto num = GENERATE(map<int>([](std::string const& line) { return std::stoi(line); },
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lines("fake-file")));
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REQUIRE(num > 0);
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}
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// Compiling and running this file will result in 4 successful assertions
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