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Catch2/projects/SelfTest/IntrospectiveTests/GeneratorsImpl.tests.cpp
Martin Hořeňovský a5a22cdadb Have the random generators use the global rng instance 
This means that if you nest multiple random generators inside one
test case, they will not return the same sequence of numbers.

Idea taken from #1736 by Amit Herman.

Closes #1736
Closes #1734
2019-10-07 21:53:07 +02:00

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#include "catch.hpp"
// Tests of generator implementation details
TEST_CASE("Generators internals", "[generators][internals]") {
using namespace Catch::Generators;
SECTION("Single value") {
auto gen = value(123);
REQUIRE(gen.get() == 123);
REQUIRE_FALSE(gen.next());
}
SECTION("Preset values") {
auto gen = values({ 1, 3, 5 });
REQUIRE(gen.get() == 1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 3);
REQUIRE(gen.next());
REQUIRE(gen.get() == 5);
REQUIRE_FALSE(gen.next());
}
SECTION("Generator combinator") {
auto gen = makeGenerators(1, 5, values({ 2, 4 }), 0);
REQUIRE(gen.get() == 1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 5);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE(gen.next());
REQUIRE(gen.get() == 4);
REQUIRE(gen.next());
REQUIRE(gen.get() == 0);
REQUIRE_FALSE(gen.next());
}
SECTION("Explicitly typed generator sequence") {
auto gen = makeGenerators(as<std::string>{}, "aa", "bb", "cc");
// This just checks that the type is std::string:
REQUIRE(gen.get().size() == 2);
// Iterate over the generator
REQUIRE(gen.get() == "aa");
REQUIRE(gen.next());
REQUIRE(gen.get() == "bb");
REQUIRE(gen.next());
REQUIRE(gen.get() == "cc");
REQUIRE_FALSE(gen.next());
}
SECTION("Filter generator") {
// Normal usage
auto gen = filter([] (int i) { return i != 2; }, values({ 2, 1, 2, 3, 2, 2 }));
REQUIRE(gen.get() == 1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 3);
REQUIRE_FALSE(gen.next());
// Completely filtered-out generator should throw on construction
REQUIRE_THROWS_AS(filter([] (int) { return false; }, value(1)), Catch::GeneratorException);
}
SECTION("Take generator") {
SECTION("Take less") {
auto gen = take(2, values({ 1, 2, 3 }));
REQUIRE(gen.get() == 1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE_FALSE(gen.next());
}
SECTION("Take more") {
auto gen = take(2, value(1));
REQUIRE(gen.get() == 1);
REQUIRE_FALSE(gen.next());
}
}
SECTION("Map with explicit return type") {
auto gen = map<double>([] (int i) {return 2.0 * i; }, values({ 1, 2, 3 }));
REQUIRE(gen.get() == 2.0);
REQUIRE(gen.next());
REQUIRE(gen.get() == 4.0);
REQUIRE(gen.next());
REQUIRE(gen.get() == 6.0);
REQUIRE_FALSE(gen.next());
}
SECTION("Map with deduced return type") {
auto gen = map([] (int i) {return 2.0 * i; }, values({ 1, 2, 3 }));
REQUIRE(gen.get() == 2.0);
REQUIRE(gen.next());
REQUIRE(gen.get() == 4.0);
REQUIRE(gen.next());
REQUIRE(gen.get() == 6.0);
REQUIRE_FALSE(gen.next());
}
SECTION("Repeat") {
SECTION("Singular repeat") {
auto gen = repeat(1, value(3));
REQUIRE(gen.get() == 3);
REQUIRE_FALSE(gen.next());
}
SECTION("Actual repeat") {
auto gen = repeat(2, values({ 1, 2, 3 }));
REQUIRE(gen.get() == 1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE(gen.next());
REQUIRE(gen.get() == 3);
REQUIRE(gen.next());
REQUIRE(gen.get() == 1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE(gen.next());
REQUIRE(gen.get() == 3);
REQUIRE_FALSE(gen.next());
}
}
SECTION("Range") {
SECTION("Positive auto step") {
SECTION("Integer") {
auto gen = range(-2, 2);
REQUIRE(gen.get() == -2);
REQUIRE(gen.next());
REQUIRE(gen.get() == -1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 0);
REQUIRE(gen.next());
REQUIRE(gen.get() == 1);
REQUIRE_FALSE(gen.next());
}
}
SECTION("Negative auto step") {
SECTION("Integer") {
auto gen = range(2, -2);
REQUIRE(gen.get() == 2);
REQUIRE(gen.next());
REQUIRE(gen.get() == 1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 0);
REQUIRE(gen.next());
REQUIRE(gen.get() == -1);
REQUIRE_FALSE(gen.next());
}
}
SECTION("Positive manual step") {
SECTION("Integer") {
SECTION("Exact") {
auto gen = range(-7, 5, 3);
REQUIRE(gen.get() == -7);
REQUIRE(gen.next());
REQUIRE(gen.get() == -4);
REQUIRE(gen.next());
REQUIRE(gen.get() == -1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE_FALSE(gen.next());
}
SECTION("Slightly over end") {
auto gen = range(-7, 4, 3);
REQUIRE(gen.get() == -7);
REQUIRE(gen.next());
REQUIRE(gen.get() == -4);
REQUIRE(gen.next());
REQUIRE(gen.get() == -1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE_FALSE(gen.next());
}
SECTION("Slightly under end") {
auto gen = range(-7, 6, 3);
REQUIRE(gen.get() == -7);
REQUIRE(gen.next());
REQUIRE(gen.get() == -4);
REQUIRE(gen.next());
REQUIRE(gen.get() == -1);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE(gen.next());
REQUIRE(gen.get() == 5);
REQUIRE_FALSE(gen.next());
}
}
}
SECTION("Negative manual step") {
SECTION("Integer") {
SECTION("Exact") {
auto gen = range(5, -7, -3);
REQUIRE(gen.get() == 5);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE(gen.next());
REQUIRE(gen.get() == -1);
REQUIRE(gen.next());
REQUIRE(gen.get() == -4);
REQUIRE_FALSE(gen.next());
}
SECTION("Slightly over end") {
auto gen = range(5, -6, -3);
REQUIRE(gen.get() == 5);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE(gen.next());
REQUIRE(gen.get() == -1);
REQUIRE(gen.next());
REQUIRE(gen.get() == -4);
REQUIRE_FALSE(gen.next());
}
SECTION("Slightly under end") {
auto gen = range(5, -8, -3);
REQUIRE(gen.get() == 5);
REQUIRE(gen.next());
REQUIRE(gen.get() == 2);
REQUIRE(gen.next());
REQUIRE(gen.get() == -1);
REQUIRE(gen.next());
REQUIRE(gen.get() == -4);
REQUIRE(gen.next());
REQUIRE(gen.get() == -7);
REQUIRE_FALSE(gen.next());
}
}
}
}
}
// todo: uncopyable type used in a generator
// idea: uncopyable tag type for a stupid generator
namespace {
struct non_copyable {
non_copyable() = default;
non_copyable(non_copyable const&) = delete;
non_copyable& operator=(non_copyable const&) = delete;
int value = -1;
};
// This class shows how to implement a simple generator for Catch tests
class TestGen : public Catch::Generators::IGenerator<int> {
int current_number;
public:
TestGen(non_copyable const& nc):
current_number(nc.value) {}
int const& get() const override;
bool next() override {
return false;
}
};
// Avoids -Wweak-vtables
int const& TestGen::get() const {
return current_number;
}
}
TEST_CASE("GENERATE capture macros", "[generators][internals][approvals]") {
auto value = GENERATE(take(10, random(0, 10)));
non_copyable nc; nc.value = value;
// neither `GENERATE_COPY` nor plain `GENERATE` would compile here
auto value2 = GENERATE_REF(Catch::Generators::GeneratorWrapper<int>(std::unique_ptr<Catch::Generators::IGenerator<int>>(new TestGen(nc))));
REQUIRE(value == value2);
}
TEST_CASE("Multiple random generators in one test case output different values", "[generators][internals][approvals]") {
SECTION("Integer") {
auto random1 = Catch::Generators::random(0, 1000);
auto random2 = Catch::Generators::random(0, 1000);
size_t same = 0;
for (size_t i = 0; i < 1000; ++i) {
same += random1.get() == random2.get();
random1.next(); random2.next();
}
// 0.5% seems like a sane bound for random identical elements within 1000 runs
REQUIRE(same < 5);
}
SECTION("Float") {
auto random1 = Catch::Generators::random(0., 1000.);
auto random2 = Catch::Generators::random(0., 1000.);
size_t same = 0;
for (size_t i = 0; i < 1000; ++i) {
same += random1.get() == random2.get();
random1.next(); random2.next();
}
// 0.5% seems like a sane bound for random identical elements within 1000 runs
REQUIRE(same < 5);
}
}
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