Add shutdown_reason Websocket command

This allows changing the normal exit reason of Websocket
processes, providing a way to signal other processes of
why the exit occurred.

test/handlers/ws_shutdown_reason_commands_h.erl

@@ -0,0 +1,38 @@
+%% This module sends the process pid to the test pid
+%% found in the x-test-pid header, then changes the
+%% shutdown reason and closes the connection normally.
+
+-module(ws_shutdown_reason_commands_h).
+-behavior(cowboy_websocket).
+
+-export([init/2]).
+-export([websocket_init/1]).
+-export([websocket_handle/2]).
+-export([websocket_info/2]).
+
+init(Req, RunOrHibernate) ->
+	TestPid = list_to_pid(binary_to_list(cowboy_req:header(<<"x-test-pid">>, Req))),
+	{cowboy_websocket, Req, {TestPid, RunOrHibernate}}.
+
+websocket_init(State={TestPid, RunOrHibernate}) ->
+	TestPid ! {ws_pid, self()},
+	ShutdownReason = receive
+		{TestPid, SR} ->
+			SR
+	after 1000 ->
+		error(timeout)
+	end,
+	Commands = [
+		{shutdown_reason, ShutdownReason},
+		close
+	],
+	case RunOrHibernate of
+		run -> {Commands, State};
+		hibernate -> {Commands, State, hibernate}
+	end.
+
+websocket_handle(_, State) ->
+	{[], State}.
+
+websocket_info(_, State) ->
+	{[], State}.

test/ws_handler_SUITE.erl

@@ -52,7 +52,8 @@ init_dispatch(Name) ->
 		{"/info", ws_info_commands_h, RunOrHibernate},
 		{"/active", ws_active_commands_h, RunOrHibernate},
 		{"/deflate", ws_deflate_commands_h, RunOrHibernate},
-		{"/set_options", ws_set_options_commands_h, RunOrHibernate}
+		{"/set_options", ws_set_options_commands_h, RunOrHibernate},
+		{"/shutdown_reason", ws_shutdown_reason_commands_h, RunOrHibernate}
 	]}]).
 
 %% Support functions for testing using Gun.
@@ -286,3 +287,21 @@ websocket_set_options_idle_timeout(Config) ->
 	after 2000 ->
 		error(timeout)
 	end.
+
+websocket_shutdown_reason(Config) ->
+	doc("The command {shutdown_reason, any()} can be used to "
+		"change the shutdown reason of a Websocket connection."),
+	ConnPid = gun_open(Config),
+	StreamRef = gun:ws_upgrade(ConnPid, "/shutdown_reason", [
+		{<<"x-test-pid">>, pid_to_list(self())}
+	]),
+	{upgrade, [<<"websocket">>], _} = gun:await(ConnPid, StreamRef),
+	WsPid = receive {ws_pid, P} -> P after 1000 -> error(timeout) end,
+	MRef = monitor(process, WsPid),
+	WsPid ! {self(), {?MODULE, ?FUNCTION_NAME}},
+	receive
+		{'DOWN', MRef, process, WsPid, {shutdown, {?MODULE, ?FUNCTION_NAME}}} ->
+			ok
+	after 1000 ->
+		error(timeout)
+	end.