resend terminal disconnect

Summary:
- if we are in the process of connecting when user invokes async_disconnect we should send a disconnect packet after connect completes
- move integration disconnect tests to integration folder

Reviewers: ivica

Reviewed By: ivica

Subscribers: korina

Differential Revision: https://repo.mireo.local/D28119

include/async_mqtt5/impl/disconnect_op.hpp

@@ -98,14 +98,17 @@ public:
 		_svc_ptr->async_send(
 			wire_data,
 			no_serial, send_flag::terminal,
-			asio::consign(
-				asio::prepend(std::move(*this), on_disconnect {}),
-				std::move(disconnect)
+			asio::prepend(
+				std::move(*this),
+				on_disconnect {}, std::move(disconnect)
 			)
 		);
 	}
 
-	void operator()(on_disconnect, error_code ec) {
+	void operator()(
+		on_disconnect,
+		control_packet<allocator_type> disconnect, error_code ec
+	) {
 		// The connection must be closed even
 		// if we failed to send the DISCONNECT packet
 		// with Reason Code of 0x80 or greater.
@@ -116,14 +119,17 @@ public:
 		)
 			return complete(asio::error::operation_aborted);
 
+		if (ec == asio::error::try_again) {
+			if (_context.terminal)
+				return send_disconnect(std::move(disconnect));
+			return complete(error_code {});
+		}
+
 		if (_context.terminal) {
 			_svc_ptr->cancel();
 			return complete(error_code {});
 		}
 
-		if (ec == asio::error::try_again)
-			return complete(error_code {});
-
 		_svc_ptr->close_stream();
 		_svc_ptr->open_stream();
 

include/async_mqtt5/mqtt_client.hpp

@@ -872,8 +872,8 @@ public:
 	 *
 	 *	\par Completion condition
 	 *	The asynchronous operation will complete when one of the following conditions is true:\n
-	 *		- The Client has attempted to send a \__DISCONNECT\__ packet, regardless of whether
-	 *		the sending was successful or not.\n
+	 *		- The Client has sent a \__DISCONNECT\__ packet.\n
+	 *		- 5 seconds have elapsed without a successful send.\n
 	 *		- An error occurred. This is indicated by an associated \__ERROR_CODE\__ in the handler.\n
 	 *
 	 *	\par Error codes