Fixed an issue with the preservation of whitespaces for strings. The validation may be invalid when one of the previous calls to the saveValue was done and the value was taking more characters. A test is now added in order to reproduce this error.

unittests/basic_string.cpp

@@ -225,3 +225,47 @@ BOOST_AUTO_TEST_CASE( xml_char_issue109 )
     test_ws_in_out<cereal::XMLInputArchive, cereal::XMLOutputArchive>( char( chars[i] ) );
   }
 }
+
+template <class IArchive, class OArchive, class Out, size_t Nb, class In = Out>
+void test_ws_in_out_array(Out const (&o_a_value_with_ws)[Nb])
+{
+    std::ostringstream os;
+    {
+        OArchive oar(os);
+        for (const auto& o_value_with_ws : o_a_value_with_ws)
+        {
+            oar(o_value_with_ws);
+        }
+    }
+
+    In i_a_value_with_ws[Nb];
+
+    std::istringstream is(os.str());
+    {
+        IArchive iar(is);
+        for (In& i_value_with_ws : i_a_value_with_ws)
+        {
+            iar(i_value_with_ws);
+        }
+    }
+
+    for (size_t uiIndex = 0; uiIndex < Nb; ++uiIndex)
+    {
+        BOOST_CHECK_EQUAL(i_a_value_with_ws[uiIndex], o_a_value_with_ws[uiIndex]);
+    }
+}
+
+BOOST_AUTO_TEST_CASE(xml_string_issue_consecutive_calls)
+{
+    std::string strings[] = {
+        "some text",
+        " some text",
+        " some text ",
+        "Long text without ws at the end",
+        "some text ",
+        " some text",
+        " some text ",
+    };
+
+    test_ws_in_out_array<cereal::XMLInputArchive, cereal::XMLOutputArchive>(strings);
+}