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🕵️ allows you to see internal calls, events and storage operations in the console
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zemse/hardhat-tracer
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Allows you to see events, calls and storage operations when running your tests.
Step 1: Install the package
npm i hardhat-tracerStep 2: Add to yourhardhat.config.js file
require("hardhat-tracer");npx hardhattest --traceError# prints calls for failed txsnpx hardhattest --fulltraceError# prints calls and storage ops for failed txsnpx hardhattest --trace# prints calls for all txsnpx hardhattest --fulltrace# prints calls and storage ops for all txsnpx hardhattest --v# same as --traceErrornpx hardhattest --vv# same as --fulltraceErrornpx hardhattest --vvv# same as --tracenpx hardhattest --vvvv# same as --fulltrace# specify opcodenpx hardhattest --v --opcodes ADD,SUB# shows any opcode specified for only failed txsnpx hardhattest --vvv --opcodes ADD,SUB# shows any opcode specified for all txs
You can just enable trace some code snippet in your tests:
hre.tracer.enabled=true;awaitmyContract.doStuff(val2);hre.tracer.enabled=false;
You can trace a mainnet transaction and ABIs/artifacts in your project and 4byte directory will be used to decode the internal message calls.
npx hardhat trace --hash 0xTransactionHash# works if mainnet fork is onnpx hardhat trace --hash 0xTransactionHash --rpc https://url# must be archive node
Note: you can also usestate overrides to override any state, e.g. things like adding console logs to the contracts involved in the trace or change balances.
You can trace a call on mainnet and ABIs/artifacts in your project and 4byte directory will be used to decode the internal message calls.
npx hardhat tracecall --to 0xAddr --data 0xData --from 0xAddr --value 123# works if mainnet fork is onnpx hardhat tracecall --to 0xAddr --data 0xData --opcodes SLOAD --rpc https://url --blocknumber 1200000# must be archive node
Note: you can also usestate overrides to override any state, e.g. things like adding console logs to the contracts involved in the trace or change balances.
If you are just looking for a quick decode of calldata, return data orSolidity"s Custom Error:
$ npx hardhat decode --data 0x095ea7b300000000000000000000000068b3465833fb72a70ecdf485e0e4c7bd8665fc45ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffERC20.approve(spender=0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45, amount=115792089237316195423570985008687907853269984665640564039457584007913129639935)$ npx hardhat decode --data 0x3850c7bd --returndata 0x000000000000000000000000000000000000000000024d0fa9cd4ba6ff769172fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffcdea1000000000000000000000000000000000000000000000000000000000000a244000000000000000000000000000000000000000000000000000000000000ff78000000000000000000000000000000000000000000000000000000000000ffff00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001IUniswapV3Pool.slot0() => (sqrtPriceX96: 2781762795090269932261746, tick: -205151, observationIndex: 41540, observationCardinality: 65400, observationCardinalityNext: 65535, feeProtocol: 0, unlocked: true)For decoding logs
$ npx hardhat decodelog 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef 0xdCB90A71Db48D673A9A483c9F355EBaE93F66A86 0x0D0707963952f2fBA59dD06f2b425ace40b492Fe --data 0x00000000000000000000000000000000000000000000054b40b1f852bd800000Transfer(src: 0xdCB90A71Db48D673A9A483c9F355EBaE93F66A86, dst: 0x0D0707963952f2fBA59dD06f2b425ace40b492Fe, wad: 24999999999999997902848)You can set display names / name tags for unknown addresses by adding new entry tohre.tracer.nameTags object in your test cases, see following example:
hre.tracer.nameTags[this.arbitrager.address]="Arbitrager";
or can be set in hardhat config
tracer:{nameTags:{"0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266":"Hunter",[someVariable]:"MyContract",},},
These state overrides are applied when the EthereumJS/VM is created inside hardhat.
tracer:{stateOverrides:{"0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2":{storage:{"0":100,"0x1abf42a573070203916aa7bf9118741d8da5f9522f66b5368aa0a2644f487b38":0,},bytecode:"0x30FF",balance:parseEther("2"),nonce:2},[someAddress]:{bytecode:"MyContract"// will compile and use the bytecode and link any libraries needed}},},
Allows to add a test case to check whether last tx did an internal message call.
expect(hre.tracer.lastTrace()).to.have.messageCall(awaitcontract.populateTransaction.getData(),{returnData:defaultAbiCoder.encode(["uint"],["1234"]),from:otherContract.address,isDelegateCall:true,isStaticCall:true,isSuccess:true,});
You can programatically access detail information about previous traces in your test cases.
import{CallItem}from'hardhat-tracer'// can be a read call, estimate gas, write txawaitcontract.method()// traverse to the right location in the trace and extract the gasUsedconsttrace1=hre.tracer.lastTrace()!;constcallItem=trace1.top?.children?.[0].children?.[0]asCallItem;constgasUsed=callItem.params.gasUsed!;
If you are runningnpx hardhat node --trace, then you can also access last trace using the rpc calltracer_lastTrace.
// hardhat configtracer:{tasks:["deploy","mycooltask"],},
This allows to run
npx hardhat deploy --tracenpx hardhat mycooltask --tracePlease note that hardhat-tracer will only be able to print trace for things that run on the EthereumJS VM inside Hardhat Network. So if your custom task is executing evm code somewhere else e.g. deploying on live network (instead of hardhat network), then this option would not be able to print trace.
Set theDEBUG env variable tohardhat-tracer:*. This will print debug logs related to internal logic in hardhat-tracer for debugging purposes.
DEBUG=hardhat-tracer:* npx hardhattest --trace
List of supported configs is available inTracerEnvUser.
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🕵️ allows you to see internal calls, events and storage operations in the console