Check price queue is empty when switching to v3

src/config_wrapper.cpp

@@ -219,6 +219,7 @@ uint64_t config_wrapper::get_evm_version_and_maybe_promote() {
 
 void config_wrapper::set_evm_version(uint64_t new_version) {
     eosio::check(new_version <= eosevm::max_eos_evm_version, "Unsupported version");
+    eosio::check(new_version != 3 || _cached_config.queue_front_block.value() == 0, "price queue must be empty");
     auto current_version = get_evm_version_and_maybe_promote();
     eosio::check(new_version > current_version, "new version must be greater than the active one");
     _cached_config.evm_version->update([&](auto& v) {

tests/gas_fee_tests.cpp

@@ -413,11 +413,6 @@ try {
    auto cfg = get_config();
    BOOST_CHECK_EQUAL(cfg.queue_front_block.value(), 0);
 
-   eosevm::block_mapping bm(cfg.genesis_time.sec_since_epoch());
-
-   setversion(3, evm_account_name);
-   produce_blocks(2);
-
    const auto one_gwei =  1'000'000'000ull;
    const auto ten_gwei = 10'000'000'000ull;
 
@@ -434,6 +429,24 @@ try {
       transfer_token("alice"_n, evm_account_name, make_asset(1), evm_account_name.to_string());
    };
 
+   eosevm::block_mapping bm(cfg.genesis_time.sec_since_epoch());
+
+   setversion(2, evm_account_name);
+   produce_blocks(2);
+
+   // Price queue must be empty before switching to v3
+   setfeeparams({.gas_price = ten_gwei});
+   BOOST_REQUIRE_EXCEPTION(setversion(3, evm_account_name),
+                           eosio_assert_message_exception,
+                           eosio_assert_message_is("price queue must be empty"));
+   produce_blocks(400);
+   trigger_prices_queue_processing();
+   cfg = get_config();
+   BOOST_CHECK_EQUAL(cfg.queue_front_block.value(), 0);
+
+   setversion(3, evm_account_name);
+   produce_blocks(2);
+
    // Queue change of gas_prices to overhead_price=10Gwei storage_price=1Gwei
    setgasprices({.overhead_price = ten_gwei, .storage_price = one_gwei});
    auto t1 = (control->pending_block_time()+fc::seconds(prices_queue_grace_period)).time_since_epoch().count();