Improved unit test of CRC chekcing in bloom filter

Confirm the impact of bit-flipping in the bloom filter

src/leveled_codec.erl

@@ -40,6 +40,7 @@
         is_active/2,
         endkey_passed/2,
         key_dominates/2,
+        maybe_reap_expiredkey/2,
         print_key/1,
         to_ledgerkey/3,
         to_ledgerkey/5,
@@ -86,6 +87,20 @@ key_dominates(LeftKey, RightKey) ->
             right_hand_dominant
     end.
 
+
+maybe_reap_expiredkey(KV, IsBasement) ->
+    Status = strip_to_statusonly(KV),
+    maybe_reap(Status, IsBasement).
+
+maybe_reap({_, infinity}, _) ->
+    false; % key is not set to expire
+maybe_reap({_, TS}, {basement, CurrTS}) when CurrTS > TS ->
+    true; % basement and ready to expire
+maybe_reap(tomb, {basement, _CurrTS}) ->
+    true; % always expire in basement
+maybe_reap(_, _) ->
+    false.
+
 is_active(Key, Value) ->
     case strip_to_statusonly({Key, Value}) of
         {active, infinity} ->