MB-67857: ns_node_disco should depend on ns_node_disco_events

The order of dependency of these two processes in mock_helpers was the
wrong way round.

This can cause a race in the initialisation of ns_node_disco, causing
flaky tests.

Change-Id: I1e1fc51f764bacc1182fe471ca5f11f5b9461c9c
Reviewed-on: https://review.couchbase.org/c/ns_server/+/232524
Well-Formed: Build Bot <[email protected]>
Well-Formed: Restriction Checker
Tested-by: Peter Searby <[email protected]>
Reviewed-by: Steve Watanabe <[email protected]>

Author: Peter-Searby

src/menelaus_cbauth.erl

@@ -669,7 +669,7 @@ setup_t() ->
     fake_chronicle_kv:setup(),
     %% Test setups return a map of pids for later shutdown in the teardown
     PidMap = mock_helpers:setup_mocks([json_rpc_events,
-                                       ns_node_disco_events,
+                                       ns_node_disco,
                                        user_storage_events,
                                        ssl_service_events,
                                        json_rpc_connection_sup,

test/mock_helpers.erl

@@ -151,15 +151,14 @@ compat_mode_events(PidMap) ->
     PidMap#{?FUNCTION_NAME => CompatModeEventsPid}.
 
 ns_node_disco(PidMap) ->
-    setup_mocks([dist_manager], PidMap),
+    PidMap0 = setup_mocks([dist_manager, ns_node_disco_events], PidMap),
     {ok, NsNodeDiscoPid} = ns_node_disco:start_link(),
-    PidMap#{?FUNCTION_NAME => NsNodeDiscoPid}.
+    PidMap0#{?FUNCTION_NAME => NsNodeDiscoPid}.
 
 ns_node_disco_events(PidMap) ->
-    PidMap0 = setup_mocks([ns_node_disco], PidMap),
     {ok, NSNodeDiscoEventsPid} = gen_event:start_link({local,
                                                        ?FUNCTION_NAME}),
-    PidMap0#{?FUNCTION_NAME => NSNodeDiscoEventsPid}.
+    PidMap#{?FUNCTION_NAME => NSNodeDiscoEventsPid}.
 
 json_rpc_events(PidMap) ->
     {ok, JsonRpcEventsPid} = gen_event:start_link({local, ?FUNCTION_NAME}),