Foundry Book

mockCallRevert

Signature

function mockCallRevert(address where, bytes calldata data, bytes calldata retdata) external;

function mockCallRevert(
    address where,
    uint256 value,
    bytes calldata data,
    bytes calldata retdata
) external;

Description

Reverts all calls to an address where if the call data either strictly or loosely matches data and returns retdata.

retdata can be a raw return message or a custom error.

When a call is made to where the call data is first checked to see if it matches in its entirety with data. If not, the call data is checked to see if there is a partial match, with the match starting at the first byte of the call data.

If a match is found, then the call is reverted and retdata is returned.

Using the second signature we can mock the calls with a specific msg.value. Calldata match takes precedence over msg.value in case of ambiguity.

Reverted mock calls are in effect until clearMockedCalls is called.

ℹ️ Internal calls

This cheatcode does not currently work on internal calls. See issue #432.

Examples

Reverting an exact call with a raw error message:

function testMockCallRevert() public {
    vm.mockCallRevert(
        address(0),
        abi.encodeWithSelector(MyToken.balanceOf.selector, address(1)),
        abi.encode("REVERT_MESSAGE")
    );
    vm.expectRevert("REVERT_MESSAGE");
    IERC20(address(0)).balanceOf(address(1));
}

Reverting a call with a custom error:

function testMockCallRevertWithCustomError() public {
    bytes memory customError = abi.encodeWithSelector(TestError.selector, "ERROR_MESSAGE");
    vm.mockCallRevert(
        address(0),
        abi.encodeWithSelector(MyToken.balanceOf.selector, address(1)),
        customError
    );
    vm.expectRevert(customError);
    IERC20(address(0)).balanceOf(address(1));
}

Mocking a call with a given msg.value:

function testMockCallRevertWithValue() public {
    assertEq(example.pay{value: 10}(1), 1);
    assertEq(example.pay{value: 1}(2), 2);
    vm.mockCallRevert(
        address(example),
        10,
        abi.encodeWithSelector(example.pay.selector),
        "ERROR_MESSAGE"
    );
    assertEq(example.pay{value: 1}(2), 2);
    vm.expectRevert("ERROR_MESSAGE");
    assertEq(example.pay{value: 10}(1), 99);
}