From d8ada22704f098f58b2784779e91011d0bd8c47f Mon Sep 17 00:00:00 2001
From: Oleh Nikolaiev <oleg@skalelabs.com>
Date: Thu, 7 Sep 2023 12:33:05 +0100
Subject: [PATCH 1/3] 1637 use 21k for gasEstimateStep if gas used is less

---
 libethereum/ClientBase.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libethereum/ClientBase.cpp b/libethereum/ClientBase.cpp
index a20c2f9b3..6d646f45a 100644
--- a/libethereum/ClientBase.cpp
+++ b/libethereum/ClientBase.cpp
@@ -132,7 +132,7 @@ std::pair< u256, ExecutionResult > ClientBase::estimateGas( Address const& _from
             estimateGasStep( upperBound, bk, _from, _dest, _value, gasPrice, _data );
         if ( estimatedStep.first ) {
             auto executionResult = estimatedStep.second;
-            auto gasUsed = executionResult.gasUsed.convert_to< int64_t >();
+            auto gasUsed = std::max( executionResult.gasUsed.convert_to< int64_t >(), lowerBound );
 
             estimatedStep = estimateGasStep( gasUsed, bk, _from, _dest, _value, gasPrice, _data );
             if ( estimatedStep.first ) {

From d01b21bf79e4130cb2383b9f8ed15bc1be091171 Mon Sep 17 00:00:00 2001
From: Oleh Nikolaiev <oleg@skalelabs.com>
Date: Thu, 7 Sep 2023 19:36:33 +0100
Subject: [PATCH 2/3] 1637 add unittest

---
 test/unittests/libweb3jsonrpc/jsonrpc.cpp | 58 +++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/test/unittests/libweb3jsonrpc/jsonrpc.cpp b/test/unittests/libweb3jsonrpc/jsonrpc.cpp
index aaee07279..1ff35dc63 100644
--- a/test/unittests/libweb3jsonrpc/jsonrpc.cpp
+++ b/test/unittests/libweb3jsonrpc/jsonrpc.cpp
@@ -1804,6 +1804,64 @@ contract Logger{
     BOOST_REQUIRE_EQUAL(logs.size(), 24);
 }
 
+BOOST_AUTO_TEST_CASE( estimate_gas_low_gas_txn ) {
+    JsonRpcFixture fixture;
+    dev::eth::simulateMining( *( fixture.client ), 10 );
+
+    auto senderAddress = fixture.coinbase.address();
+
+/*
+// SPDX-License-Identifier: None
+pragma solidity ^0.6.0;
+
+contract TestEstimateGas {
+    uint256[256] number;
+    uint256 counter = 0;
+
+    function store(uint256 x) public {
+        number[counter] = x;
+        counter += 1;
+    }
+
+    function clear(uint256 pos) public {
+        number[pos] = 0;
+    }
+}
+*/
+
+    string bytecode = "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";
+
+    Json::Value create;
+    create["code"] = bytecode;
+    create["gas"] = "180000";  // TODO or change global default of 90000?
+
+    string deployHash = fixture.rpcClient->eth_sendTransaction( create );
+    dev::eth::mineTransaction( *( fixture.client ), 1 );
+
+    Json::Value deployReceipt = fixture.rpcClient->eth_getTransactionReceipt( deployHash );
+    string contractAddress = deployReceipt["contractAddress"].asString();
+
+    Json::Value txStore1;  // call store(1)
+    txStore1["to"] = contractAddress;
+    txStore1["data"] = "0x6057361d0000000000000000000000000000000000000000000000000000000000000001";
+    txStore1["from"] = toJS( senderAddress );
+    txStore1["gasPrice"] = fixture.rpcClient->eth_gasPrice();
+    string txHash = fixture.rpcClient->eth_call( txStore1, "latest" );
+
+    Json::Value estimateGasCall;  // call clear(0)
+    estimateGasCall["to"] = contractAddress;
+    estimateGasCall["data"] = "0xc0fe1af80000000000000000000000000000000000000000000000000000000000000000";
+    estimateGasCall["from"] = toJS( senderAddress );
+    estimateGasCall["gasPrice"] = fixture.rpcClient->eth_gasPrice();
+    string estimatedGas = fixture.rpcClient->eth_estimateGas( estimateGasCall );
+
+    dev::bytes data = dev::jsToBytes( estimateGasCall["data"].asString() );
+
+    BOOST_REQUIRE( dev::jsToU256( estimatedGas ) > dev::eth::TransactionBase::baseGasRequired(
+                       false, &data, fixture.client->chainParams().scheduleForBlockNumber(
+                           fixture.client->number() ) ) );
+}
+
 BOOST_AUTO_TEST_CASE( storage_limit_contract ) {
     JsonRpcFixture fixture;
     dev::eth::simulateMining( *( fixture.client ), 10 );

From b232296706dc7c8533734902b06fc2dfa5f07808 Mon Sep 17 00:00:00 2001
From: Oleh Nikolaiev <oleg@skalelabs.com>
Date: Thu, 7 Sep 2023 20:02:43 +0100
Subject: [PATCH 3/3] 1637 add unittest

---
 test/unittests/libweb3jsonrpc/jsonrpc.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/unittests/libweb3jsonrpc/jsonrpc.cpp b/test/unittests/libweb3jsonrpc/jsonrpc.cpp
index 1ff35dc63..fd7df6a06 100644
--- a/test/unittests/libweb3jsonrpc/jsonrpc.cpp
+++ b/test/unittests/libweb3jsonrpc/jsonrpc.cpp
@@ -1860,6 +1860,7 @@ contract TestEstimateGas {
     BOOST_REQUIRE( dev::jsToU256( estimatedGas ) > dev::eth::TransactionBase::baseGasRequired(
                        false, &data, fixture.client->chainParams().scheduleForBlockNumber(
                            fixture.client->number() ) ) );
+    BOOST_REQUIRE( dev::jsToU256( estimatedGas ) == 21871 );
 }
 
 BOOST_AUTO_TEST_CASE( storage_limit_contract ) {