[5200] Addressed review comments: expanded commentary in UnixDomainSocket.

src/lib/asiolink/testutils/test_server_unix_socket.cc

@@ -52,6 +52,13 @@ public:
 
     /// @brief Handler invoked when data have been received over the socket.
     ///
+    /// This is the handler invoked when the data have been received over the
+    /// socket. If custom response has been specified, this response is sent
+    /// back to the client. Otherwise, the handler echoes back the request
+    /// and prepends the word "received ". Finally, it calls a custom
+    /// callback function (specified in the constructor) to notify that the
+    /// response has been sent over the socket.
+    ///
     /// @param bytes_transferred Number of bytes received.
     void
     readHandler(const boost::system::error_code&, size_t bytes_transferred) {

src/lib/asiolink/testutils/test_server_unix_socket.h

@@ -22,6 +22,22 @@ namespace test {
 class ConnectionPool;
 
 /// @brief Provides unix domain socket functionality for unit tests.
+///
+/// This class represents a server side socket. It can be used to
+/// test client's transmission over the unix domain socket. By default,
+/// the server side socket echoes the client's message so the client's
+/// message (prefixed with the word "received").
+///
+/// It is also possible to specify a custom response from the server
+/// instead of eachoing back the request.
+///
+/// It is possible to make multiple connections to the server side
+/// socket simultaneously.
+///
+/// The test should perform IOService::run_one until it finds that
+/// the number of responses sent by the server is greater than
+/// expected. The number of responses sent so far can be retrieved
+/// using @ref TestServerUnixSocket::getResponseNum.
 class TestServerUnixSocket {
 public:
 
@@ -34,7 +50,7 @@ public:
     TestServerUnixSocket(IOService& io_service,
                          const std::string& socket_file_path,
                          const long test_timeout,
-                         const std::string& custom_respons_ = "");
+                         const std::string& custom_response = "");
 
     /// @brief Destructor.
     ///