Added tests for function_output_iterator.

test/function_output_iterator_cf.cpp

@@ -0,0 +1,37 @@
+// Copyright 2022 (c) Andrey Semashev
+// Distributed under the Boost Software License Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/iterator/function_output_iterator.hpp>
+
+namespace {
+
+struct sum_func
+{
+    typedef void result_type;
+
+    explicit sum_func(int& n) : m_n(n) {}
+    result_type operator() (int x) const
+    {
+        m_n += x;
+    }
+
+private:
+    int& m_n;
+};
+
+} // namespace
+
+int main()
+{
+    int n = 0;
+    boost::iterators::function_output_iterator< sum_func > it1 =
+        boost::iterators::make_function_output_iterator(sum_func(n));
+    boost::iterators::function_output_iterator< sum_func > it2 =
+        boost::iterators::make_function_output_iterator(sum_func(n));
+
+    *it1 = *it2;
+
+    return 0;
+}