tests: respect naming conventions and improve nesting of some test suites

Change-Id: I255c27b552b32570871a9d5f8bda814ba8723c80
Refs: #2497
diff --git a/tests/unit-tests/encoding/buffer-stream.t.cpp b/tests/unit-tests/encoding/buffer-stream.t.cpp
index 2e37e25..9c712ea 100644
--- a/tests/unit-tests/encoding/buffer-stream.t.cpp
+++ b/tests/unit-tests/encoding/buffer-stream.t.cpp
@@ -65,6 +65,9 @@
   auto os = make_unique<OBufferStream>();
   *os << 'x';
   os.reset(); // should not cause use-after-free
+
+  // avoid "test case [...] did not check any assertions" message from Boost.Test
+  BOOST_CHECK(true);
 }
 
 BOOST_AUTO_TEST_SUITE_END() // TestBufferStream