Add dummy unit test for set matching

Author: geo2a

booster/unit-tests/Test/Booster/Pattern/MatchRewrite.hs

@@ -32,6 +32,7 @@ test_match_rewrite =
         , sorts
         , injections
         , internalLists
+        , internalSets
         , internalMaps
         ]
 
@@ -376,6 +377,17 @@ internalLists =
 
     klist = KList testKListDef
 
+internalSets :: TestTree
+internalSets =
+    testGroup
+        "Internal sets"
+        [ test
+            "Can match an empty set with itself"
+            emptySet
+            emptySet
+            (success [])
+        ]
+
 internalMaps :: TestTree
 internalMaps =
     testGroup