Improvements to code coverage:

More tests and test cases are added to bring up
the percentage of library code covered by tests.

test/websocket/detail/mask.cpp

@@ -0,0 +1,48 @@
+//
+// Copyright (c) 2013-2016 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// 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 <beast/websocket/detail/mask.hpp>
+#include <beast/unit_test/suite.hpp>
+
+namespace beast {
+namespace websocket {
+namespace detail {
+
+class mask_test : public beast::unit_test::suite
+{
+public:
+    struct test_generator
+    {
+        using result_type = std::uint32_t;
+
+        result_type n = 0;
+
+        void
+        seed(std::seed_seq const&)
+        {
+        }
+
+        std::uint32_t
+        operator()()
+        {
+            return n++;
+        }
+    };
+
+    void run() override
+    {
+        maskgen_t<test_generator> mg;
+        expect(mg() != 0);
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(mask,websocket,beast);
+
+} // detail
+} // websocket
+} // beast
+