Merge pull request #4241 from esl/muc-suite-fix-init-per-group

Fix flaky `init_per_group` in the MUC suite

This PR fixes a problem where tests might fail if an HTTP listener has already been started in the init_per_group function of the MUC suite.

Sometimes, if other tests that need an HTTP listener don't work right, they can leave the listener running. This causes a problem when trying to start it again in the init_per_group.

big_tests/tests/http_helper.erl

@@ -25,8 +25,16 @@
 start(Port, Path, HandleFun) ->
     application:ensure_all_started(cowboy),
     Dispatch = cowboy_router:compile([{'_', [{Path, http_helper, HandleFun}]}]),
-    {ok, _} = cowboy:start_clear(http_helper_listener, [{port, Port}],
-                                 #{env => #{dispatch => Dispatch}}).
+    case cowboy:start_clear(http_helper_listener, [{port, Port}],
+                            #{env => #{dispatch => Dispatch}}) of
+        {ok, Pid} ->
+            {ok, Pid};
+        {error, {already_started, _}} ->
+            ct:log("http_helper_listener was already running. Restarting it."),
+            stop(),
+            {ok, _} = cowboy:start_clear(http_helper_listener, [{port, Port}],
+                                         #{env => #{dispatch => Dispatch}})
+    end.
 
 stop() ->
     cowboy:stop_listener(http_helper_listener).

big_tests/tests/muc_SUITE.erl

@@ -341,7 +341,6 @@ end_per_suite(Config) ->
     dynamic_modules:restore_modules(Config),
     escalus:end_per_suite(Config).
 
-
 init_per_group(room_registration_race_condition, Config) ->
     escalus_fresh:create_users(Config, [{alice, 1}]);