Fix tallyingTests and switch to OUnit2

tests/libtest/tallyingTest.ml

-(* TODO: Switch to OUnit2 when tests are fixed, then use tools/install_hooks.sh -d to check tallying before a commit *)
-open OUnit(*2*)
+open OUnit2
 open Types
 
 let parse_typ s =
@@ -201,7 +200,7 @@ let norm_tests () = [
   ];
 
   "(`$A -> `$B) -> [ `$A ] -> [ `$B ]", "((Int -> Bool) | ((`$A \\ Int) -> (`$B \\ Int))) -> `$Gamma", mk_s [
-    [P(V "A","Empty")]
+    [P(V "A","Empty");N("[`$A] -> [`$B]", V "Gamma")]
   ];
 
   "Int -> Bool", "`$A", mk_s [[N("Int -> Bool",V "A")]];
@@ -490,7 +489,7 @@ let suite =
   ]
 
 let main () =
-  OUnit(*2*).run_test_tt_main suite
+  OUnit2.run_test_tt_main suite
 ;;
 
 main ()