test commentBefore

for issue #203
diff --git a/src/test_lib_json/main.cpp b/src/test_lib_json/main.cpp
index a52cc78..3dff874 100644
--- a/src/test_lib_json/main.cpp
+++ b/src/test_lib_json/main.cpp
@@ -1541,6 +1541,22 @@
   }
 }
 
+JSONTEST_FIXTURE(ValueTest, CommentBefore) {
+  Json::Value val; // fill val
+  val.setComment("// this comment should appear before", Json::CommentPlacement::commentBefore);
+  // Configure the Builder, then ...
+  Json::StreamWriterBuilder wbuilder;
+  wbuilder.settings_["commentStyle"] = "All";
+  char const expected[] = "// this comment should appear before\nnull";
+  std::string result = Json::writeString(wbuilder, val);
+  JSONTEST_ASSERT_STRING_EQUAL(expected, result);
+  std::string res2 = val.toStyledString();
+  std::string exp2 = "\n";
+  exp2 += expected;
+  exp2 += "\n";
+  JSONTEST_ASSERT_STRING_EQUAL(exp2, res2);
+}
+
 JSONTEST_FIXTURE(ValueTest, zeroes) {
   std::string binary("hi", 3);  // include trailing 0
   JSONTEST_ASSERT_EQUAL(3, binary.length());
@@ -2239,6 +2255,7 @@
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, offsetAccessors);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, typeChecksThrowExceptions);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, StaticString);
+  JSONTEST_REGISTER_FIXTURE(runner, ValueTest, CommentBefore);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, zeroes);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, zeroesInKeys);