The gen Namespace

The gen namespace provides convenient collection for all built-in generators and combinators in cppproptest. The gen namespace is designed to provide a unified, user-friendly interface for accessing generators and combinators. Instead of writing verbose built-in arbitrary names like Arbi<int>(), you can use more intuitive names like gen::int32() or gen::arbitrary<int>.

Note: All functions in the gen namespace are aliases to the original proptest namespace functions. The original names remain available for backward compatibility.

Generators

To use the gen namespace, simply include the main header and use the gen:: prefix:

#include "proptest/proptest.hpp"

using namespace proptest;

// Use gen namespace for cleaner syntax
auto intGen = gen::int32();
auto stringGen = gen::string();
auto vectorGen = gen::vector<int>();

Combinators

// Constants and choices
auto constantGen = gen::just(42);
auto choiceGen = gen::elementOf<int>(1, 3, 5, 7, 11, 13, 17, 19);
auto unionGen = gen::oneOf<int>(
    gen::interval<int>(1, 10),
    gen::interval<int>(100, 110)
);

// Object construction
struct Point { Point(int x, int y) : x(x), y(y) {} int x, y; };
auto pointGen = gen::construct<Point, int, int>(
    gen::interval<int>(-10, 10),
    gen::interval<int>(-10, 10)
);

// Filtering and transformation
auto evenGen = gen::filter<int>(gen::int32(), [](int n) { return n % 2 == 0; });
auto positiveGen = gen::suchThat<int>(gen::int32(), [](int n) { return n > 0; });
auto stringFromIntGen = gen::transform<int, std::string>(
    gen::int32(),
    [](int n) { return std::to_string(n); }
);

Dependencies and Complex Generators

// Size-dependent vector
auto sizeAndVectorGen = gen::dependency<int, std::vector<int>>(
    gen::interval<int>(1, 5),
    [](int size) { return gen::vector<int>().setSize(size); }
);

// Complex nested structure
auto complexGen = gen::vector<gen::map<std::string, gen::vector<int>>>();

Property Tests

// Simple property test
forAll([](int x, int y) {
    return x + y == y + x;  // Commutativity of addition
}, gen::interval<int>(-100, 100), gen::interval<int>(-100, 100));

// Property test with custom generators
forAll([](std::vector<int> vec) {
    if (vec.empty()) return true;
    auto sorted = vec;
    std::sort(sorted.begin(), sorted.end());
    return sorted.size() == vec.size();
}, gen::vector<int>().setSize(0, 10));