Fixes to beast::asio::streambuf:

* Fix to_string conversion
* Fix assert on debug invariant checks
* Fix the treatment of the output position when the entire output is committed.
* Add unit test

beast/asio/tests/streambuf.test.cpp

@@ -0,0 +1,78 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of Beast: https://github.com/vinniefalco/Beast
+    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <beast/asio/streambuf.h>
+#include <beast/unit_test/suite.h>
+
+namespace beast {
+namespace asio {
+
+class streambuf_test : public unit_test::suite
+{
+public:
+    // Convert a ConstBufferSequence to a string
+    template <class ConstBufferSequence>
+    static
+    std::string
+    to_str (ConstBufferSequence const& b)
+    {
+        std::string s;
+        auto const n = boost::asio::buffer_size(b);
+        s.resize(n);
+        boost::asio::buffer_copy(
+            boost::asio::buffer(&s[0], n), b);
+        return s;
+    }
+
+    void run()
+    {
+        {
+            beast::asio::streambuf b(10);
+            std::string const s = "1234567890";
+            b << s;
+            expect (to_str(b.data()) == s);
+            b.prepare(5);
+        }
+
+        {
+            beast::asio::streambuf b(10);
+            b.prepare(10);
+            b.commit(10);
+            b.consume(10);
+        }
+
+        {
+            beast::asio::streambuf b(5);
+            boost::asio::buffer_copy(b.prepare(14),
+                boost::asio::buffer(std::string("1234567890ABCD")));
+            b.commit(4);
+            expect(to_str(b.data()) == "1234");
+            b.consume(4);
+            b.commit(10);
+            expect(to_str(b.data()) == "567890ABCD");
+        }
+
+        pass();
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(streambuf,asio,beast);
+
+}
+}