Getting "Provider not found" while testing my contract with waffle

Question

I am testing my contract using Waffle and I am following the documentation provided, using const provider = new MockProvider(); to get a provider for testing.

An error was raised in expect().catch() and it says that "Provider not found". Before trying to catch it, I had a more annoying warning that told me to handle errors and this is what I get after handling them.

Everything seems to work as expected but I would like to get rid of this stuff.

I let my code bellow

it("Shall fund the contract", async () => 
      {
        const contract = await deployContract() 
    
        const address = "0x5FbDB2315678afecb367f032d93F642f64180aa3";
    
        const provider = new MockProvider();
        const [wallet, otherWallet] = provider.getWallets();
    
        tx = {
          to: address,
          value: utils.parseEther("3.0")
        }
    
        await wallet.signTransaction(tx);
        
        const walletTo = "0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266";
    
        expect(await wallet.sendTransaction(tx)).to.changeEtherBalance(walletTo, 3)
        .then()
        .catch((err) => 
        {
          //console.log(err)
        });
      })

Answer 1

changeEtherBalance expects a contract or a signer rather than a string. If you are checking if the contract is funded, then rather than a hardcoded address, use contrat.address. You can then pass contract into the changeEtherBalance

const address = contract.address;
// Send to address....
changeEtherBalance(contract, ....

If you don't care about the to address and any random address works for the purposes of the test, then you can use:

const walletTo = provider.createEmptyWallet();
const address = walletTo.address;

If you want to use that specific address, it seem slike changeEtherBalance expects, as an API, a signer or contract interface. You would need the private key or mnemonic and call:

const walletTo = new ethers.Wallet(privKey, provider);
const address = walletTo.address;

Optionally, you can just rewrite your test to call

const newBalance = await provider.getBalanceOf(walletTo);

And use a normal math expect.