Testing the Ability to Reject a Transaction with Insufficient Gas

This test ensures that MetaMask provides adequate protection against a common user error: attempting to send a transaction with an ETH balance that is insufficient to cover the combined amount being sent and the network gas fee. The tester should try to send an amount of ETH that is very close to the total wallet balance, leaving little to no room for the gas fee. When the user proceeds to confirm the transaction, the application must not allow it to be signed and broadcast. Instead, it should present a clear and prominent error message before the final signing step, stating that the account has “Insufficient balance for transaction” or “Insufficient funds for gas.” This pre-flight check is crucial to prevent users from wasting gas on transactions that are doomed to fail, which would still cost them the gas fee without completing the intended transfer. The wallet must accurately calculate the maximum total cost (amount + gas) and compare it against the current balance. Explanations of gas and failed transactions are available at metamask.