From eb00700c002cf9d5ccff54ae3f47b81d37de9709 Mon Sep 17 00:00:00 2001
From: HuangYi <huang@crypto.com>
Date: Tue, 14 Dec 2021 15:25:25 +0800
Subject: [PATCH] Problem: empty topics in rpc response is not tested

Closes: #841

Solution:
- merge empty topics fix
- add integration tests to verify
---
 .../contracts/contracts/TestERC20Utility.sol  |  5 +++++
 integration_tests/test_basic.py               | 20 +++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/integration_tests/contracts/contracts/TestERC20Utility.sol b/integration_tests/contracts/contracts/TestERC20Utility.sol
index 29e9f436dc..e81fcca8ae 100644
--- a/integration_tests/contracts/contracts/TestERC20Utility.sol
+++ b/integration_tests/contracts/contracts/TestERC20Utility.sol
@@ -27,4 +27,9 @@ contract TestERC20Utility is ERC20 {
         _burn(msg.sender, total);
         emit __CronosSendToEthereum(recipient, amount, bridge_fee);
     }
+
+    function test_log0() public {
+        bytes32 data = "hello world";
+        log0(bytes32(data));
+    }
 }
diff --git a/integration_tests/test_basic.py b/integration_tests/test_basic.py
index 1f430e35c8..7c2f35e7a4 100644
--- a/integration_tests/test_basic.py
+++ b/integration_tests/test_basic.py
@@ -454,3 +454,23 @@ def test_suicide(cluster):
     assert receipt.status == 1
 
     assert len(w3.eth.get_code(destroyee.address)) == 0
+
+
+def test_log0(cluster):
+    """
+    test compliance of empty topics behavior
+    """
+    w3 = cluster.w3
+    contract = deploy_contract(
+        w3,
+        Path(__file__).parent
+        / "contracts/artifacts/contracts/TestERC20Utility.sol/TestERC20Utility.json",
+    )
+    tx = contract.functions.test_log0().buildTransaction({"from": ADDRS["validator"]})
+    receipt = send_transaction(w3, tx, KEYS["validator"])
+    assert len(receipt.logs) == 1
+    log = receipt.logs[0]
+    assert log.topics == []
+    assert (
+        log.data == "0x68656c6c6f20776f726c64000000000000000000000000000000000000000000"
+    )