Error: Transaction reverted: function selector was not recognized and there's no fallback nor receive function

Question

I'm getting a console error in hardhat test case this is my solidity code

/**
 * donateToCampaign - Allows a user to donate to a specific campaign.
 *
 * @param _id the ID of the campaign to donate to.
 */
function donateToCampaign(uint256 _id) public payable noReentrancy {
    uint256 amount = msg.value;

    Campaign storage campaign = campaigns[_id];

    require(
        campaign.status != CampaignStatus.Close,
        "This campaign is not open to fund."
    );

    require(
        campaign.deadline > block.timestamp &&
            isCampaignOpen(campaign.status),
        "The campaign is not open or has reached its goal."
    );

    require(
        campaign.amountCollected + amount <= campaign.target,
        "Donation exceeds campaign target."
    );

    campaign.amountCollected += amount;
    campaign.donators.push(payable(msg.sender));
    campaign.donations.push(amount);

    if (campaign.amountCollected == campaign.target) {
        campaign.status = CampaignStatus.Successful;
        emit CampaginSuccessfullyFunded(campaign);
    }

    payable(address(this)).transfer(amount);
}

and the test case in hardhat using chai

 it("should allow a user to donate to a campaign", async () => {
const target = ethers.utils.parseEther("1");
await contract.connect(aliceAccount).createCampaign(
  "Test Campaign",
  "Test Description",
  target,
  "testimage.jpg"
);
let cc = await contract.campaigns(0);
const tx = await contract
  .connect(bobAccount)
  .donateToCampaign(0, { value: ethers.utils.parseEther("0.5") });
const campaign = await contract.campaigns(0);
expect(campaign.amountCollected).to.equal(ethers.utils.parseEther("0.5"));

});

Answer 1

You do not need to transfer the value if the value is sent in a payable method No need: payable(address(this)).transfer(amount)

If you really want to use this then you have to define a fallback function to receive ether.

Eg.

........
receive() payable external {}
........

Fallback function is necessary to receive any amount of ether. Otherwise you can not send ether to the smart contract using wallet like metamask.

Answer 2

I believe the error comes from the last line of your function.

payable(address(this)).transfer(amount); // Also why tf are you doing that?

Here, your contract is trying to call its own fallback ( or receive) function, if it doesnt exist, the whole call would revert with this error message.

Also, unrelated, but why are you using a nonReentrant modifier inside a function that doesn't make any external calls?

Answer 3

Update the smart contract address after deployment in your tests. It seems like the contract address is hardcoded.