# mockCalls

Description: mockCalls cheatcode documentation

Note: This document was authored using MDX

  Source: https://github.com/NomicFoundation/hardhat-website/tree/main/src/content/docs/docs/reference/cheatcodes/Environment/mock-calls.mdx

  Components used in this page:
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{/* This document contains content copied/adapted from the Foundry Book (MIT licensed). See LICENSE in the parent directory. */}

### Signature

```solidity
function mockCalls(
  address where,
  bytes calldata data,
  bytes[] calldata retdata
) external;
```

```solidity
function mockCalls(
  address where,
  uint256 value,
  bytes calldata data,
  bytes[] calldata retdata
) external;
```

### Description

Mocks all calls to an address `where` if the call data either strictly or loosely
matches `data` and returns different data for each call based on the `retdata`
array values.

See [`mockCall`](/docs/reference/cheatcodes/environment/mock-call) for more information on mocking calls and
matching precedence.

:::note
Any invocation of the mocked call beyond the number of elements in `retdata`
will receive the last `retdata` element in response. `clearMockedCalls` can be
called to clear the mock
:::

### Examples

Mocking multiple `balanceOf(address)` calls:

```solidity
function testMockCall() public {
  bytes[] memory mocks = new bytes[](2);
  mocks[0] = abi.encode(2 ether);
  mocks[1] = abi.encode(1 ether);

  vm.mockCalls(
    address(0),
    abi.encodeWithSelector(IERC20.balanceOf.selector, address(1)),
    mocks
  );

  assertEq(IERC20(address(0)).balanceOf(address(1)), 2 ether);
  assertEq(IERC20(address(0)).balanceOf(address(1)), 1 ether);
}
```

Mocking multiple calls with `msg.value`:

```solidity
function testMockCallsWithMsgValue() public {
  bytes[] memory mocks = new bytes[](2);
  mocks[0] = abi.encode(2 ether);
  mocks[1] = abi.encode(1 ether);

  vm.mockCalls(
    address(0),
    1 ether,
    abi.encodeWithSelector(DexPool.swapETHForToken.selector),
    mocks
  );

  uint tokenAmount1 = DexPool(address(0)).swapETHForToken{ value: 1 ether }();
  uint tokenAmount2 = DexPool(address(0)).swapETHForToken{ value: 1 ether }();

  assertEq(tokenAmount1, 2 ether);
  assertEq(tokenAmount2, 1 ether);
}
```