Function test_container_iterators_with_shared_ptr

tests/test_container_helpers.h:367–390

// Verifies: begin/end, forward iteration, const iteration, move leaves empty
template<typename Container>
void test_container_iterators_with_shared_ptr() {
    auto ptr1 = make_shared_int(10);
    auto ptr2 = make_shared_int(20);
    auto ptr3 = make_shared_int(30);

    Container source;
    populate(source, ptr1);
    populate(source, ptr2);
    populate(source, ptr3);

    // Test mutable iterators exist
    FL_CHECK(source.begin() != source.end());

    // Test const iterators via const reference
    const auto& const_source = source;
    FL_CHECK(const_source.begin() != const_source.end());

    // Move and verify source is empty via iterators
    Container destination = fl::move(source);
    FL_CHECK(source.begin() == source.end());  // Empty after move
    const auto& const_empty = source;
    FL_CHECK(const_empty.begin() == const_empty.end());
    FL_CHECK(destination.begin() != destination.end());  // Has elements
}

// Test reverse iterator support for bidirectional containers
// Verifies: rbegin/rend exist and work correctly after move