In my contract I have a modifier that doesn't allow for other contracts to call the function

modifier callerIsUser() {
    require(tx.origin == msg.sender, "The caller cannot be another contract");

Let's assume the method it's being used in is here

contract MyToken {
    // ...
    constructor(a,b,c,d) ERC721A("name", "MTK") {
       // assigns the a, b, c, d variables

    function mint() callerIsUser {}

How can I write a test to make sure it reverts? I tried deploying a mock contract to call it but this errors (not the error I'm looking for).

await expect(
  token.connect(mockContract).mint()).to.be.revertedWith("The caller cannot be another contract");
// Error: invalid signer or provider 

await expect(
  token.attach(mockContract.address).mint()).to.be.revertedWith("The caller cannot be another contract");
// Error: Transaction reverted: function selector was not recognized and there's no fallback function

So I think I need to create a mock Contract that takes in the address of the original contract and call the function but I'm confused how to do so...

contract MyTokenMock is MyToken {
    address public myTokenAddress;

    constructor(address myTokenAddress_) {
        myTokenAddress = myTokenAddress_;

    function mint () {
        // How do I call the token address here?

2 Answers 2


I ended up figuring out how to create a mock contract. Essentially create an interface of the actual contract. Use it as a template for your mock contract. Pass in the address in the constructor and instantiate it with the template and then call it as if calling the deployed contract.

interface IMyToken {
    function mint() {} external payable;

contract Mock {
    IMyToken public myToken;

    constructor(address payable myTokenAddress) payable {
        myToken = IMyToken(myTokenAddress);

    function mint() public payable {

According to this answer https://ethereum.stackexchange.com/a/139774/18153 on a similar question you could use impersonateAccounts from hardhat-network-helpers-library and connect to your token-instance like this:

   await helpers.impersonateAccount(contractAddress);
   const contractSigner = await ethers.getSigner(contractAddress);
   await token.connect(contractSigner)

(Cudos and credits to Franco Victorio)

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