anchor.diff:      {error, ttl_expired} = aetx:check(RTx5, Trees, 2, ?PROTOCOL_VERSION),
       ok.
   
  -register_oracle(_Cfg) ->
  +register_oracle_negative_dynamic_fee(_Cfg) ->
       {PubKey, S1} = aeo_test_utils:setup_new_account(aeo_test_utils:new_state()),
  -    Tx           = aeo_test_utils:register_tx(PubKey, S1),
  +    Trees        = aeo_test_utils:trees(S1),
  +    CurrHeight   = ?ORACLE_REG_HEIGHT,
  +
  +    F = fun(RegTxOpts) -> aetx:check(aeo_test_utils:register_tx(PubKey, RegTxOpts, S1), Trees, CurrHeight, ?PROTOCOL_VERSION) end,
  +    1 = MinFee = aec_governance:minimum_tx_fee(),
  +
  +    %% Test minimum fee for increasing TTL.
  +    ?assertEqual({error, too_low_fee}, F(#{oracle_ttl => {delta, 0}, fee => 0})),
  +    ?assertMatch({ok, _}             , F(#{oracle_ttl => {delta, 0}, fee => MinFee})),
  +    ?assertEqual({error, too_low_fee}, F(#{oracle_ttl => {delta, 1}, fee => MinFee})),
  +    ?assertMatch({ok, _}             , F(#{oracle_ttl => {delta, 1}, fee => 1 + MinFee})),
  +    ?assertMatch({ok, _}             , F(#{oracle_ttl => {delta, 999}, fee => 1 + MinFee})),
  +    ?assertMatch({ok, _}             , F(#{oracle_ttl => {delta, 1000}, fee => 1 + MinFee})),
  +    ?assertEqual({error, too_low_fee}, F(#{oracle_ttl => {delta, 1001}, fee => 1 + MinFee})),
  +    ?assertMatch({ok, _}             , F(#{oracle_ttl => {delta, 1001}, fee => 2 + MinFee})),
  +    %% Test more than minimum fee considering TTL.
  +    ?assertMatch({ok, _}             , F(#{oracle_ttl => {delta, 1001}, fee => 3 + MinFee})),
  +    ok.
  +
  +register_oracle(Cfg) ->
  +    register_oracle(Cfg, #{}).
  +
  +register_oracle(_Cfg, RegTxOpts) ->
  +    {PubKey, S1} = aeo_test_utils:setup_new_account(aeo_test_utils:new_state()),
  +    Tx           = aeo_test_utils:register_tx(PubKey, RegTxOpts, S1),
       PrivKey      = aeo_test_utils:priv_key(PubKey, S1),
   
       %% Test that RegisterTX is accepted
  
positive.code:         , prune_response_long/1
          , query_oracle/1
          , query_oracle_negative/1
          , query_response/1
          , query_response_negative/1
          , register_oracle/1
          , register_oracle_negative/1
          ]).
  
  -include_lib("common_test/include/ct.hrl").
  
  -include_lib("apps/aecore/include/blocks.hrl").
  -include_lib("apps/aeoracle/include/oracle_txs.hrl").
  
negative.code: %% test case exports
  -export([ extend_oracle/1
          , extend_oracle_negative/1
          , extend_oracle_negative_dynamic_fee/1
          , prune_oracle/1
          , prune_oracle_extend/1
          , prune_query/1
  