Decoding Hardhat Test Output: A Complete Guide to Contract Health and Gas Costs

Compilation and Test Results

npx hardhat test
Compiled 1 Solidity file successfully (evm target: paris).

  Lock
    Deployment
      ✔ Should set the right unlockTime (58ms)
      ✔ Should set the right owner
      ✔ Should receive and store the funds to lock
      ✔ Should fail if the unlockTime is not in the future
    Withdrawals
      Validations
        ✔ Should revert with the right error if called too soon
        ✔ Should revert with the right error if called from another account
        ✔ Shouldn't fail if the unlockTime has arrived and the owner calls it
      Events
        ✔ Should emit an event on withdrawals
      Transfers
        ✔ Should transfer the funds to the owner

  9 passing (121ms)

The output shows that Hardhat compiled a single Solidity source targeting the Paris EVM version and then executed a hierarchical test suite for the Lock contract. All nine test cases passed, indicating functional correctness for deployment, owner assignment, fund locking, time‑based withdrawal validation, event emission, and fund transfer.

Gas Reporter Output

Solidity and Network Settings

Solidity: 0.8.28

– compiler version used for the build. Optim: false – optimizer disabled; production builds typically enable it ( true) to reduce gas. Runs: 200 – optimizer parameter that assumes each function will be called 200 times (relevant only when Optim is true). viaIR: false – compilation did not use the intermediate‑representation pipeline. Block: 30,000,000 gas – simulated block gas limit for the test environment.

Method Gas Consumption

withdraw – average gas consumption 34,096 gas per call, with 7 total invocations during the test run.

The report also lists minimum, maximum, and average values for each external/public function, as well as the number of calls. The USD column is empty because no gas price was configured.

Deployment Gas Consumption

Average deployment cost for the Lock contract: 326,112 gas .

This represents 1.1 % of the simulated block gas limit, a useful metric for assessing whether the contract size may cause deployment failures on networks with tighter limits.

Key Takeaways

Functional correctness: All nine test cases passed, confirming that the contract behaves as expected under both positive and negative scenarios.

Test coverage: The suite covers deployment state, owner assignment, fund locking, time‑based withdrawal validation, event emission, and fund transfer, providing a solid baseline for contract quality.

Performance and cost insights: The average gas cost of the withdraw function (34 k gas) and the deployment cost (326 k gas) highlight optimization opportunities. High deployment gas may suggest contract splitting or storage layout refinement, while unusually high function gas warrants a deeper code review for inefficiencies.

Regularly running npx hardhat test and reviewing the Hardhat gas reporter output enables developers to iteratively improve smart contract security, reliability, and cost efficiency before main‑net deployment.