[sites] Complicate the test: tring to load same library twice

It should make @ejgallego less worried

Signed-off-by: Dmitrii Kosarev <Dmitrii.Kosarev@pm.me>

otherlibs/site/test/plugin_require_thread.t/plugin2/dune

@@ -0,0 +1,15 @@
+(env
+ (_
+  (flags -w -33)))
+
+(library
+ (public_name plugin2.plugin2_impl)
+ (name plugin2_impl)
+ (modules plugin2_impl)
+ (libraries app.MyControls app.register result threads))
+
+(plugin
+ (name plugin2)
+ (libraries threads plugin2.plugin2_impl)
+ (site
+  (app plugins)))

otherlibs/site/test/plugin_require_thread.t/plugin2/dune-project

@@ -0,0 +1,8 @@
+(lang dune 2.8)
+
+(using dune_site 0.1)
+
+(generate_opam_files true)
+
+(package
+ (name plugin2))

otherlibs/site/test/plugin_require_thread.t/plugin2/plugin2_impl.ml

@@ -0,0 +1,3 @@
+let () =
+  print_endline "Registration of Plugin2";
+  Queue.add (fun () -> print_endline "Plugin2 is doing something...") Registration.todo

otherlibs/site/test/plugin_require_thread.t/run.t

@@ -1,13 +1,17 @@
 
   $ dune build ./app.exe @install
   $ dune exec ./app.exe
+  The library is being used by two plugins finished initialization
   Fatal error: exception Dune_site_plugins__Plugins.Thread_library_required_by_plugin_but_not_required_by_main_executable
   [2]
 
   $ sed -i -e "s/;TOREMOVE//" dune
 
   $ dune build ./app.exe @install
   $ dune exec ./app.exe
+  The library is being used by two plugins finished initialization
   Registration of Plugin1
+  Registration of Plugin2
   Main app starts...
   Plugin1 is doing something...
+  Plugin2 is doing something...

otherlibs/site/test/plugin_require_thread.t/stubs/MyControls.ml

@@ -0,0 +1 @@
+let () = print_endline "The library is being used by two plugins finished initialization"

otherlibs/site/test/plugin_require_thread.t/stubs/dune

@@ -1,5 +1,5 @@
 (library
  (public_name app.MyControls)
  (name MyControls)
- (modules)
+ (modules MyControls)
  (libraries))