Class counting_executor

test/source/tests/timer_tests/timer_tests.cpp:58–90

    };

    class counting_executor : public concurrencpp::executor {

       private:
        std::atomic_size_t m_invocation_count;

       public:
        counting_executor() : executor("counting executor"), m_invocation_count(0) {}

        void enqueue(concurrencpp::task task) override {
            ++m_invocation_count;
            task();
        }

        void enqueue(std::span<concurrencpp::task>) override {
            // do nothing
        }

        int max_concurrency_level() const noexcept override {
            return 0;
        }

        bool shutdown_requested() const noexcept override {
            return false;
        }

        void shutdown() noexcept override {
            // do nothing
        }

        size_t invocation_count() const noexcept {
            return m_invocation_count.load();
        }
    };

    class recording_executor : public concurrencpp::executor {