Ultra-simple string class

string.hpp

#ifndef TEXT_STRING_HPP
#define TEXT_STRING_HPP

#include <algorithm>
#include <cstring>
#include <iterator>
#include <memory>
#include <iosfwd>

namespace text {

class string {
public:
    typedef unsigned char value_type;
    typedef std::size_t size_type;

    string() : m_length(), m_buffer(new value_type[1]) {
        m_buffer[0] = '\0';
    }

    string(char const* str)
        : m_length(std::strlen(str))
        , m_buffer(new value_type[m_length + 1])
    {
        std::copy(str, str + m_length + 1, &m_buffer[0]);
    }

    string(string const& other)
        : m_length(other.m_length)
        , m_buffer(new value_type[m_length + 1])
    {
        std::copy(&other.m_buffer[0],
                  &other.m_buffer[m_length] + 1,
                  &m_buffer[0]);
    }

    string(string&& other) /*noexcept*/ = default;

    string& operator =(string other) noexcept {
        m_length = std::move(other.m_length);
        m_buffer = std::move(other.m_buffer);
        return *this;
    }

    //string& operator =(string&&) noexcept = default;

    size_type length() const { return m_length; }

    friend std::ostream& operator <<(std::ostream& out, string const& str) {
        std::copy(&str.m_buffer[0],
             &str.m_buffer[str.length()],
             std::ostream_iterator<char>(out, ""));
        return out;
    }

private:
    size_type m_length;
    std::unique_ptr<value_type[]> m_buffer;
};

} // namespace text

#endif // ndef TEXT_STRING_HPP

test.cpp

#include <iostream>

#include "string.hpp"

#define DEBUG(str) std::cout << "> " << #str << " = \"" << str << "\"\n"

void f(text::string&& str) {
    DEBUG(str);
}

int main() {
    using text::string;
    using std::cout;

    string s1;
    string s2 = "Hello";

    DEBUG(s1);
    DEBUG(s2);

    s1 = s2;

    cout << "s1 = s2\n";
    DEBUG(s1);
    DEBUG(s2);

    s1 += " world";

    cout << "s1 += \" world\"\n";
    DEBUG(s1);
    DEBUG(s2);

    string s3(s1);

    cout << "string s3(s1)\n";
    DEBUG(s1);
    DEBUG(s2);
    DEBUG(s3);

    string s4 = std::move(s3);
    s1 = std::move(s2);

    cout << "string s4 = std::move(s3)\n";
    cout << "s1 = std::move(s2)\n";
    DEBUG(s1);
    DEBUG(s2);
    DEBUG(s3);
    DEBUG(s4);

    cout << "f(\"test\")\n";
    f("test");
}