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## Testing User Operation Validation in Your Smart Contract Account In the world of account abstraction (ERC-4337), ensuring your smart contract account correctly validates user operations is paramount. This lesson focuses on a critical test, `testValidationOfUserOps`, designed to verify that your `MinimalAccount.sol` contract can successfully validate a user operation when invoked by the `EntryPoint` contract. This step is crucial for security and proper functioning within the ERC-4337 ecosystem. The core logic of this test involves three main steps: 1. Signing a user operation with the account owner's key. 2. Simulating a call from the `EntryPoint` to the `validateUserOp` function on your smart contract account, passing the signed user operation. 3. Asserting that the `validateUserOp` function returns the expected value, signifying successful validation. Let's break down the `testValidationOfUserOps` function, which follows the standard Arrange-Act-Assert pattern. ### The `testValidationOfUserOps` Function: A Deep Dive This function meticulously prepares the ground, executes the action, and then verifies the outcome. **1. Arrange Phase: Setting the Stage** To streamline our testing process, much of the setup code is efficiently reused from a previous test, `testRecoverSignedOp`. This phase prepares all necessary components for the validation call. * **Initial State Check:** We begin by asserting that the `minimalAccount` initially holds zero USDC, ensuring a clean state for our test. ```solidity assertEq(usdc.balanceOf(address(minimalAccount)), 0); ``` * **Operation Parameters:** We define the parameters for the user operation. In this example, the operation intends to mint USDC to the `minimalAccount`. * `dest`: The target address for the operation (the USDC contract). * `value`: The amount of Ether to send with the call (0 in this case). * `functionData`: The encoded call data for the `mint` function on the `IERC20Mock` (USDC) contract. ```solidity address dest = address(usdc); uint256 value = 0; bytes memory functionData = abi.encodeWithSelector(IERC20Mock.mint.selector, address(minimalAccount), AMOUNT); ``` * **Encoding `executeCallData`:** This is the payload that the `MinimalAccount.execute` function will eventually process. It bundles the `dest`, `value`, and `functionData`. ```solidity bytes memory executeCallData = abi.encodeWithSelector(MinimalAccount.execute.selector, dest, value, functionData); ``` * **Generating a Signed `PackedUserOperation`:** Using a helper function (`sendPackedUserOp.generateSignedUserOperation`), we create a `PackedUserOperation` (named `packedUserOp`). This structure contains the `executeCallData` and, crucially, is signed by the designated owner of the `minimalAccount`. ```solidity PackedUserOperation memory packedUserOp = sendPackedUserOp.generateSignedUserOperation(executeCallData, helperConfig.getConfig()); ``` * **Calculating `userOperationHash`:** The `EntryPoint` contract calculates a unique hash for each user operation. We replicate this by calling `getUserOpHash` on an `IEntryPoint` interface, passing our `packedUserOp`. ```solidity bytes32 userOperationHash = IEntryPoint(helperConfig.getConfig().entryPoint).getUserOpHash(packedUserOp); ``` * **Defining `missingAccountFunds`:** This parameter is part of the `validateUserOp` signature and relates to the pre-funding mechanism where the account might need to compensate the `EntryPoint` for gas. For this specific test, its precise value isn't critical to the validation logic itself, so an arbitrary value like `1e18` is used. The focus here is on the account's ability to correctly process the validation request, not the gas payment details. ```solidity uint256 missingAccountFunds = 1e18; ``` Here's the complete Arrange section: ```solidity function testValidationOfUserOps() public { // Arrange assertEq(usdc.balanceOf(address(minimalAccount)), 0); address dest = address(usdc); uint256 value = 0; bytes memory functionData = abi.encodeWithSelector(IERC20Mock.mint.selector, address(minimalAccount), AMOUNT); bytes memory executeCallData = abi.encodeWithSelector(MinimalAccount.execute.selector, dest, value, functionData); PackedUserOperation memory packedUserOp = sendPackedUserOp.generateSignedUserOperation(executeCallData, helperConfig.getConfig()); bytes32 userOperationHash = IEntryPoint(helperConfig.getConfig().entryPoint).getUserOpHash(packedUserOp); uint256 missingAccountFunds = 1e18; ``` **2. Act Phase: Simulating the EntryPoint's Call** This is where the core interaction occurs. We simulate the `EntryPoint` contract calling the `validateUserOp` function on our `MinimalAccount`. * **`vm.prank(address(helperConfig.getConfig().entryPoint));`**: This Foundry cheatcode is essential. The `validateUserOp` function in `MinimalAccount.sol` includes a `requireFromEntryPoint` modifier. This modifier ensures that only the `EntryPoint` contract can successfully call this function by checking `msg.sender`. The `vm.prank` cheatcode spoofs the `msg.sender` for the *next* contract call, making it appear as if the `EntryPoint` (specified by `helperConfig.getConfig().entryPoint`) is the caller. * **`uint256 validationData = minimalAccount.validateUserOp(packedUserOp, userOperationHash, missingAccountFunds);`**: With the `msg.sender` correctly spoofed, we call `validateUserOp` on the `minimalAccount`. We pass the `packedUserOp` we prepared, its corresponding `userOperationHash`, and the `missingAccountFunds`. The return value, `validationData`, is captured for assertion. The Act section: ```solidity // Act vm.prank(address(helperConfig.getConfig().entryPoint)); uint256 validationData = minimalAccount.validateUserOp( packedUserOp, userOperationHash, missingAccountFunds ); ``` **3. Assert Phase: Verifying the Outcome** The final step is to assert that the `validateUserOp` function behaved as expected. * **Understanding Validation Return Values:** In our `MinimalAccount.sol` (and its associated `Helpers.sol`), `SIG_VALIDATION_SUCCESS` is defined as `0`, while `SIG_VALIDATION_FAILED` is `1`. The internal `_validateSignature` function within `MinimalAccount.sol`, which is called by `validateUserOp`, returns `0` if the signature within the `packedUserOp` correctly matches the account's owner. * **`assertEq(validationData, 0);`**: This assertion checks if the `validationData` returned by `validateUserOp` is `0`. A value of `0` signifies that the user operation was successfully validated (i.e., the signature was correct). The Assert section: ```solidity // Assert assertEq(validationData, 0); } ``` It's worth noting that the ERC-4337 standard allows `validationData` to be a more complex packed `uint256`. This packed value can convey richer information, such as a `sigAuthorizer`, `validUntil` (timestamp for operation expiry), and `validAfter` (timestamp for when the operation becomes valid), as hinted in the `IAccount.sol` interface comments. However, for this minimal implementation, we simplify this to a binary outcome: `0` for success and `1` for failure. ### Running the Test To execute this specific test and confirm its successful execution, you would use the following Foundry command: `forge test -mt testValidationOfUserOps` A passing test indicates that your `MinimalAccount.sol`'s `validateUserOp` function correctly validates a properly signed user operation when called by the `EntryPoint`. ### Key Concepts Recap This test highlights several fundamental concepts in account abstraction: * **`validateUserOp` Function:** This is the cornerstone function within a smart contract account responsible for validating incoming user operations. It typically checks signatures and nonces (though nonce checking was commented out in this particular `MinimalAccount` implementation for simplicity in earlier stages) and can also handle logic related to pre-funding requirements. * **`EntryPoint` Interaction:** The `EntryPoint` contract is the sole, trusted entity designated to call `validateUserOp` on smart contract accounts. This controlled interaction is key to the ERC-4337 architecture. * **`vm.prank` for Testing:** When testing functions that restrict callers based on `msg.sender` (like those with an "onlyEntryPoint" modifier), Foundry's `vm.prank` cheatcode is indispensable for simulating calls from specific addresses. * **Packed Validation Data:** The `uint256` returned by `validateUserOp` serves as a status indicator. While it can be a simple success/failure flag in minimal implementations, the standard allows for it to be a packed data structure conveying more granular validation information. * **User Operation Lifecycle:** This test fits into the broader lifecycle of a user operation: 1. A user signs a `UserOperation`. 2. A Bundler (an off-chain actor in an Alt-Mempool) submits this `UserOperation` to the `EntryPoint` contract on-chain. 3. The `EntryPoint` calls `validateUserOp` on the target smart contract account. 4. If validation is successful, the `EntryPoint` proceeds to execute the operation. Successfully passing `testValidationOfUserOps` is a significant milestone, confirming a critical piece of your account abstraction wallet's security and functional correctness. ### What's Next? With user operation validation confirmed, the subsequent step is to test the execution phase. The upcoming test, `testEntryPointCanExecuteCommands`, will verify that the `EntryPoint` can take a validated user operation and successfully execute the intended command (e.g., the USDC mint) on the smart contract account. This aligns with the ERC-4337 flow where Bundlers submit operations to the `EntryPoint`, which then orchestrates validation and execution.
In the world of account abstraction (ERC-4337), ensuring your smart contract account correctly validates user operations is paramount. This lesson focuses on a critical test, testValidationOfUserOps
, designed to verify that your MinimalAccount.sol
contract can successfully validate a user operation when invoked by the EntryPoint
contract. This step is crucial for security and proper functioning within the ERC-4337 ecosystem.
The core logic of this test involves three main steps:
Signing a user operation with the account owner's key.
Simulating a call from the EntryPoint
to the validateUserOp
function on your smart contract account, passing the signed user operation.
Asserting that the validateUserOp
function returns the expected value, signifying successful validation.
Let's break down the testValidationOfUserOps
function, which follows the standard Arrange-Act-Assert pattern.
testValidationOfUserOps
Function: A Deep DiveThis function meticulously prepares the ground, executes the action, and then verifies the outcome.
1. Arrange Phase: Setting the Stage
To streamline our testing process, much of the setup code is efficiently reused from a previous test, testRecoverSignedOp
. This phase prepares all necessary components for the validation call.
Initial State Check: We begin by asserting that the minimalAccount
initially holds zero USDC, ensuring a clean state for our test.
Operation Parameters: We define the parameters for the user operation. In this example, the operation intends to mint USDC to the minimalAccount
.
dest
: The target address for the operation (the USDC contract).
value
: The amount of Ether to send with the call (0 in this case).
functionData
: The encoded call data for the mint
function on the IERC20Mock
(USDC) contract.
Encoding executeCallData
: This is the payload that the MinimalAccount.execute
function will eventually process. It bundles the dest
, value
, and functionData
.
Generating a Signed PackedUserOperation
: Using a helper function (sendPackedUserOp.generateSignedUserOperation
), we create a PackedUserOperation
(named packedUserOp
). This structure contains the executeCallData
and, crucially, is signed by the designated owner of the minimalAccount
.
Calculating userOperationHash
: The EntryPoint
contract calculates a unique hash for each user operation. We replicate this by calling getUserOpHash
on an IEntryPoint
interface, passing our packedUserOp
.
Defining missingAccountFunds
: This parameter is part of the validateUserOp
signature and relates to the pre-funding mechanism where the account might need to compensate the EntryPoint
for gas. For this specific test, its precise value isn't critical to the validation logic itself, so an arbitrary value like 1e18
is used. The focus here is on the account's ability to correctly process the validation request, not the gas payment details.
Here's the complete Arrange section:
2. Act Phase: Simulating the EntryPoint's Call
This is where the core interaction occurs. We simulate the EntryPoint
contract calling the validateUserOp
function on our MinimalAccount
.
vm.prank(address(helperConfig.getConfig().entryPoint));
: This Foundry cheatcode is essential. The validateUserOp
function in MinimalAccount.sol
includes a requireFromEntryPoint
modifier. This modifier ensures that only the EntryPoint
contract can successfully call this function by checking msg.sender
. The vm.prank
cheatcode spoofs the msg.sender
for the next contract call, making it appear as if the EntryPoint
(specified by helperConfig.getConfig().entryPoint
) is the caller.
uint256 validationData = minimalAccount.validateUserOp(packedUserOp, userOperationHash, missingAccountFunds);
: With the msg.sender
correctly spoofed, we call validateUserOp
on the minimalAccount
. We pass the packedUserOp
we prepared, its corresponding userOperationHash
, and the missingAccountFunds
. The return value, validationData
, is captured for assertion.
The Act section:
3. Assert Phase: Verifying the Outcome
The final step is to assert that the validateUserOp
function behaved as expected.
Understanding Validation Return Values: In our MinimalAccount.sol
(and its associated Helpers.sol
), SIG_VALIDATION_SUCCESS
is defined as 0
, while SIG_VALIDATION_FAILED
is 1
. The internal _validateSignature
function within MinimalAccount.sol
, which is called by validateUserOp
, returns 0
if the signature within the packedUserOp
correctly matches the account's owner.
assertEq(validationData, 0);
: This assertion checks if the validationData
returned by validateUserOp
is 0
. A value of 0
signifies that the user operation was successfully validated (i.e., the signature was correct).
The Assert section:
It's worth noting that the ERC-4337 standard allows validationData
to be a more complex packed uint256
. This packed value can convey richer information, such as a sigAuthorizer
, validUntil
(timestamp for operation expiry), and validAfter
(timestamp for when the operation becomes valid), as hinted in the IAccount.sol
interface comments. However, for this minimal implementation, we simplify this to a binary outcome: 0
for success and 1
for failure.
To execute this specific test and confirm its successful execution, you would use the following Foundry command:
forge test -mt testValidationOfUserOps
A passing test indicates that your MinimalAccount.sol
's validateUserOp
function correctly validates a properly signed user operation when called by the EntryPoint
.
This test highlights several fundamental concepts in account abstraction:
validateUserOp
Function: This is the cornerstone function within a smart contract account responsible for validating incoming user operations. It typically checks signatures and nonces (though nonce checking was commented out in this particular MinimalAccount
implementation for simplicity in earlier stages) and can also handle logic related to pre-funding requirements.
EntryPoint
Interaction: The EntryPoint
contract is the sole, trusted entity designated to call validateUserOp
on smart contract accounts. This controlled interaction is key to the ERC-4337 architecture.
vm.prank
for Testing: When testing functions that restrict callers based on msg.sender
(like those with an "onlyEntryPoint" modifier), Foundry's vm.prank
cheatcode is indispensable for simulating calls from specific addresses.
Packed Validation Data: The uint256
returned by validateUserOp
serves as a status indicator. While it can be a simple success/failure flag in minimal implementations, the standard allows for it to be a packed data structure conveying more granular validation information.
User Operation Lifecycle: This test fits into the broader lifecycle of a user operation:
A user signs a UserOperation
.
A Bundler (an off-chain actor in an Alt-Mempool) submits this UserOperation
to the EntryPoint
contract on-chain.
The EntryPoint
calls validateUserOp
on the target smart contract account.
If validation is successful, the EntryPoint
proceeds to execute the operation.
Successfully passing testValidationOfUserOps
is a significant milestone, confirming a critical piece of your account abstraction wallet's security and functional correctness.
With user operation validation confirmed, the subsequent step is to test the execution phase. The upcoming test, testEntryPointCanExecuteCommands
, will verify that the EntryPoint
can take a validated user operation and successfully execute the intended command (e.g., the USDC mint) on the smart contract account. This aligns with the ERC-4337 flow where Bundlers submit operations to the EntryPoint
, which then orchestrates validation and execution.
An indispensable security walkthrough to Testing User Operation Validation in Your Smart Contract Account - Bolster your ERC-4337 smart account's security by mastering the `testValidationOfUserOps` test, ensuring correct validation of EntryPoint-invoked user operations. You'll practice signing user ops, simulating EntryPoint calls via `vm.prank`, and asserting expected validation results.
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Last updated on July 4, 2025
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Course Overview
About the course
Advanced smart contract development
How to develop a stablecoin
How to develop a DeFi protocol
How to develop a DAO
Advanced smart contracts testing
Fuzz testing
Manual verification
Web3 Developer Relations
$85,000 - $125,000 (avg. salary)
Web3 developer
$60,000 - $150,000 (avg. salary)
Smart Contract Engineer
$100,000 - $150,000 (avg. salary)
Smart Contract Auditor
$100,000 - $200,000 (avg. salary)
Security researcher
$49,999 - $120,000 (avg. salary)
Web3 engineer, educator, and Cyfrin co-founder. Patrick's smart contract development and security courses have helped hundreds of thousands of engineers kickstarting their careers into web3.
Guest lecturers:
Last updated on July 4, 2025