Merge pull request #4166 from ethereum-optimism/jm/echidna-burn

.changeset/pretty-chicken-rest.md

+---
+'@eth-optimism/ci-builder': patch
+'@eth-optimism/contracts-bedrock': patch
+---
+
+Add echidna tests for Burn

.circleci/config.yml

@@ -290,11 +290,16 @@ jobs:
 
   bedrock-echidna-run:
     docker:
-    - image: ethereumoptimism/ci-builder:latest
+      - image: ethereumoptimism/ci-builder:latest
     parameters:
       echidna_target:
         description: Which echidna fuzz contract to run
         type: string
+      size:
+        description: Custom resource class size for the run
+        type: string
+        default: large
+    resource_class: <<parameters.size>>
     steps:
       - checkout
       - attach_workspace: {at: "."}
@@ -817,6 +822,15 @@ workflows:
           echidna_target: aliasing
           requires:
             - bedrock-echidna-build
+      - bedrock-echidna-run:
+          echidna_target: "burn:eth"
+          requires:
+            - bedrock-echidna-build
+      - bedrock-echidna-run:
+          echidna_target: "burn:gas"
+          size: 2xlarge
+          requires:
+            - bedrock-echidna-build
       - op-bindings-build:
           requires:
             - yarn-monorepo

packages/contracts-bedrock/contracts/echidna/FuzzBurn.sol

+pragma solidity 0.8.15;
+
+import { Burn } from "../libraries/Burn.sol";
+import { StdUtils } from "forge-std/Test.sol";
+
+contract EchidnaFuzzBurnEth is StdUtils {
+    bool failedEthBurn;
+
+    /**
+     * @notice Takes an integer amount of eth to burn through the Burn library and
+     * updates the contract state if an incorrect amount of eth moved from the contract
+     */
+    function testBurn(uint256 _value) public {
+        // cache the contract's eth balance
+        uint256 preBurnBalance = address(this).balance;
+        uint256 value = bound(_value, 0, preBurnBalance);
+
+        // execute a burn of _value eth
+        Burn.eth(value);
+
+        // check that exactly value eth was transfered from the contract
+        unchecked {
+            if (address(this).balance != preBurnBalance - value) {
+                failedEthBurn = true;
+            }
+        }
+    }
+
+    function echidna_burn_eth() public view returns (bool) {
+        // ASSERTION: The amount burned should always match the amount passed exactly
+        return !failedEthBurn;
+    }
+}
+
+contract EchidnaFuzzBurnGas is StdUtils {
+    bool failedGasBurn;
+
+    /**
+     * @notice Takes an integer amount of gas to burn through the Burn library and
+     * updates the contract state if at least that amount of gas was not burned
+     * by the library
+     */
+    function testGas(uint256 _value) public {
+        // cap the value to the max resource limit
+        uint256 MAX_RESOURCE_LIMIT = 8_000_000;
+        uint256 value = bound(_value, 0, MAX_RESOURCE_LIMIT);
+
+        // cache the contract's current remaining gas
+        uint256 preBurnGas = gasleft();
+
+        // execute the gas burn
+        Burn.gas(value);
+
+        // cache the remaining gas post burn
+        uint256 postBurnGas = gasleft();
+
+        // check that at least value gas was burnt (and that there was no underflow)
+        unchecked {
+            if (postBurnGas - preBurnGas > value || preBurnGas - value > preBurnGas) {
+                failedGasBurn = true;
+            }
+        }
+    }
+
+    function echidna_burn_gas() public view returns (bool) {
+        // ASSERTION: The amount of gas burned should be strictly greater than the
+        // the amount passed as _value (minimum _value + whatever minor overhead to
+        // the value after the call)
+        return !failedGasBurn;
+    }
+}

packages/contracts-bedrock/package.json

@@ -40,7 +40,8 @@
     "lint": "yarn lint:fix && yarn lint:check",
     "typechain": "typechain --target ethers-v5 --out-dir dist/types --glob 'artifacts/!(build-info)/**/+([a-zA-Z0-9_]).json'",
     "echidna:aliasing": "echidna-test --contract EchidnaFuzzAddressAliasing --config ./echidna.yaml .",
-    "echidna:burn": "echidna-test --contract EchidnaFuzzBurn --config ./echidna.yaml .",
+    "echidna:burn:gas": "echidna-test --contract EchidnaFuzzBurnGas --config ./echidna.yaml .",
+    "echidna:burn:eth": "echidna-test --contract EchidnaFuzzBurnEth --config ./echidna.yaml .",
     "echidna:encoding": "echidna-test --contract EchidnaFuzzEncoding --config ./echidna.yaml .",
     "echidna:portal": "echidna-test --contract EchidnaFuzzOptimismPortal --config ./echidna.yaml .",
     "echidna:hashing": "echidna-test --contract EchidnaFuzzHashing --config ./echidna.yaml .",