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catch2/tests/SelfTest/IntrospectiveTests/GeneratorsImpl.tests.cpp
Martin Hořeňovský 0c223bb751
Decrease chance of false positive in random generator testing
2020-05-03 19:01:21 +02:00

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#include <catch2/catch_approx.hpp>
#include <catch2/catch_test_macros.hpp>
#include <catch2/generators/catch_generator_exception.hpp>
#include <catch2/generators/catch_generators_adapters.hpp>
#include <catch2/generators/catch_generators_random.hpp>
#include <catch2/generators/catch_generators_range.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("Floating Point") {
using Catch::Approx;
SECTION("Exact") {
const auto rangeStart = -1.;
const auto rangeEnd = 1.;
const auto step = .1;
auto gen = range(rangeStart, rangeEnd, step);
auto expected = rangeStart;
while( (rangeEnd - expected) > step ) {
INFO( "Current expected value is " << expected );
REQUIRE(gen.get() == Approx(expected));
REQUIRE(gen.next());
expected += step;
}
REQUIRE(gen.get() == Approx( rangeEnd ) );
REQUIRE_FALSE(gen.next());
}
SECTION("Slightly over end") {
const auto rangeStart = -1.;
const auto rangeEnd = 1.;
const auto step = .3;
auto gen = range(rangeStart, rangeEnd, step);
auto expected = rangeStart;
while( (rangeEnd - expected) > step ) {
INFO( "Current expected value is " << expected );
REQUIRE(gen.get() == Approx(expected));
REQUIRE(gen.next());
expected += step;
}
REQUIRE_FALSE(gen.next());
}
SECTION("Slightly under end") {
const auto rangeStart = -1.;
const auto rangeEnd = .9;
const auto step = .3;
auto gen = range(rangeStart, rangeEnd, step);
auto expected = rangeStart;
while( (rangeEnd - expected) > step ) {
INFO( "Current expected value is " << expected );
REQUIRE(gen.get() == Approx(expected));
REQUIRE(gen.next());
expected += step;
}
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("#1809 - GENERATE_COPY and SingleValueGenerator does not compile", "[generators][compilation][approvals]") {
// Verify Issue #1809 fix, only needs to compile.
auto a = GENERATE_COPY(1, 2);
(void)a;
auto b = GENERATE_COPY(as<long>{}, 1, 2);
(void)b;
int i = 1;
int j = 2;
auto c = GENERATE_COPY(i, j);
(void)c;
auto d = GENERATE_COPY(as<long>{}, i, j);
(void)d;
SUCCEED();
}
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();
}
// Because the previous low bound failed CI couple of times,
// we use a very high threshold of 20% before failure is reported.
REQUIRE(same < 200);
}
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();
}
// Because the previous low bound failed CI couple of times,
// we use a very high threshold of 20% before failure is reported.
REQUIRE(same < 200);
}
}
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