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// 301-Gen-MapTypeConversion.cpp
// Shows how to use map to modify generator's return type.
// Specifically we wrap a std::string returning generator with a generator
// that converts the strings using stoi, so the returned type is actually
// an int.
#include <catch2/catch.hpp>
#include <string>
#include <sstream>
// Returns a line from a stream. You could have it e.g. read lines from
// a file, but to avoid problems with paths in examples, we will use
// a fixed stringstream.
class LineGenerator : public Catch::Generators::IGenerator<std::string> {
std::string m_line;
std::stringstream m_stream;
public:
LineGenerator() {
m_stream.str("1\n2\n3\n4\n");
if (!next()) {
throw Catch::GeneratorException("Couldn't read a single line");
}
}
std::string const& get() const override;
bool next() override {
return !!std::getline(m_stream, m_line);
}
};
std::string const& LineGenerator::get() const {
return m_line;
}
// This helper function provides a nicer UX when instantiating the generator
// Notice that it returns an instance of GeneratorWrapper<std::string>, which
// is a value-wrapper around std::unique_ptr<IGenerator<std::string>>.
Catch::Generators::GeneratorWrapper<std::string> lines(std::string /* ignored for example */) {
return Catch::Generators::GeneratorWrapper<std::string>(
std::unique_ptr<Catch::Generators::IGenerator<std::string>>(
new LineGenerator()
)
);
}
TEST_CASE("filter can convert types inside the generator expression", "[example][generator]") {
auto num = GENERATE(map<int>([](std::string const& line) { return std::stoi(line); },
lines("fake-file")));
REQUIRE(num > 0);
}
// Compiling and running this file will result in 4 successful assertions
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