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#include "catch.hpp"
#include <cstring>
// Generators and sections can be nested freely
TEST_CASE("Generators -- simple", "[generators]") {
auto i = GENERATE(1, 2, 3);
SECTION("one") {
auto j = GENERATE(values({ -3, -2, -1 }));
REQUIRE(j < i);
}
SECTION("two") {
// You can also explicitly set type for generators via Catch::Generators::as
auto str = GENERATE(as<std::string>{}, "a", "bb", "ccc");
REQUIRE(4u * i > str.size());
}
}
// You can create a cartesian-product of generators by creating multiple ones
TEST_CASE("3x3x3 ints", "[generators]") {
auto x = GENERATE(1, 2, 3);
auto y = GENERATE(4, 5, 6);
auto z = GENERATE(7, 8, 9);
// These assertions will be run 27 times (3x3x3)
CHECK(x < y);
CHECK(y < z);
REQUIRE(x < z);
}
// You can also create data tuples
TEST_CASE("tables", "[generators]") {
// Note that this will not compile with libstdc++ older than libstdc++6
// See https://stackoverflow.com/questions/12436586/tuple-vector-and-initializer-list
// for possible workarounds
// auto data = GENERATE(table<char const*, int>({
// {"first", 5},
// {"second", 6},
// {"third", 5},
// {"etc...", 6}
// }));
// Workaround for the libstdc++ bug mentioned above
using tuple_type = std::tuple<char const*, int>;
auto data = GENERATE(table<char const*, int>({
tuple_type{"first", 5},
tuple_type{"second", 6},
tuple_type{"third", 5},
tuple_type{"etc...", 6}
}));
REQUIRE(strlen(std::get<0>(data)) == static_cast<size_t>(std::get<1>(data)));
}
#ifdef __cpp_structured_bindings
// Structured bindings make the table utility much nicer to use
TEST_CASE( "strlen2", "[approvals][generators]" ) {
auto [test_input, expected] = GENERATE( table<std::string, size_t>({
{"one", 3},
{"two", 3},
{"three", 5},
{"four", 4}
}));
REQUIRE( test_input.size() == expected );
}
#endif
// An alternate way of doing data tables without structured bindings
struct Data { std::string str; size_t len; };
TEST_CASE( "strlen3", "[generators]" ) {
auto data = GENERATE( values<Data>({
{"one", 3},
{"two", 3},
{"three", 5},
{"four", 4}
}));
REQUIRE( data.str.size() == data.len );
}
#ifdef __cpp_structured_bindings
// Based on example from https://docs.cucumber.io/gherkin/reference/#scenario-outline
// (thanks to https://github.com/catchorg/Catch2/issues/850#issuecomment-399504851)
// Note that GIVEN, WHEN, and THEN now forward onto DYNAMIC_SECTION instead of SECTION.
// DYNAMIC_SECTION takes its name as a stringstream-style expression, so can be formatted using
// variables in scope - such as the generated variables here. This reads quite nicely in the
// test name output (the full scenario description).
static auto eatCucumbers( int start, int eat ) -> int { return start-eat; }
SCENARIO("Eating cucumbers", "[generators][approvals]") {
auto [start, eat, left] = GENERATE( table<int,int,int> ({
{ 12, 5, 7 },
{ 20, 5, 15 }
}));
GIVEN( "there are " << start << " cucumbers" )
WHEN( "I eat " << eat << " cucumbers" )
THEN( "I should have " << left << " cucumbers" ) {
REQUIRE( eatCucumbers( start, eat ) == left );
}
}
#endif
// There are also some generic generator manipulators
TEST_CASE("Generators -- adapters", "[generators]") {
// TODO: This won't work yet, introduce GENERATE_VAR?
//auto numbers = Catch::Generators::values({ 1, 2, 3, 4, 5, 6 });
SECTION("Filtering by predicate") {
// This filters out all odd (false) numbers, giving [2, 4, 6]
auto i = GENERATE(filter([] (int val) { return val % 2 == 0; }, values({ 1, 2, 3, 4, 5, 6 })));
REQUIRE(i % 2 == 0);
}
SECTION("Shortening a range") {
// This takes the first 3 elements from the values, giving back [1, 2, 3]
auto i = GENERATE(take(3, values({ 1, 2, 3, 4, 5, 6 })));
REQUIRE(i < 4);
}
SECTION("Transforming elements") {
SECTION("Same type") {
// This doubles values [1, 2, 3] into [2, 4, 6]
auto i = GENERATE(map([] (int val) { return val * 2; }, values({ 1, 2, 3 })));
REQUIRE(i % 2 == 0);
}
SECTION("Different type") {
// This takes a generator that returns ints and maps them into strings
auto i = GENERATE(map<std::string>([] (int val) { return std::to_string(val); }, values({ 1, 2, 3 })));
REQUIRE(i.size() == 1);
}
}
SECTION("Repeating a generator") {
// This will return values [1, 2, 3, 1, 2, 3]
auto j = GENERATE(repeat(2, values({ 1, 2, 3 })));
REQUIRE(j > 0);
}
}
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