Error: could not detect network [jest] [ethers] [javascript]-CodePudding

I want to test my function getData(). This function is used to get the data 'cost' (should be 5) and 'totalSupply' (should be 50) from my smart contract.

getData: async function(){
  if(typeof window.ethereum !== 'undefined') {
    const provider = new ethers.providers.Web3Provider(window.ethereum);
    const contract = new ethers.Contract(this.contractAddress, NftContract.abi, provider); //new instance of the contract to interact with the function of the contract
    try {
      console.log('*******try');
      const cost = await contract.cost();
      const totalSupply = await contract.totalSupply();
      console.log('*******cost');
      console.log(cost);
      this.data.cost = String(cost);
      this.data.totalSupply = String(totalSupply);
    }
    catch(err) {
      console.log('error');
      console.log(err);
      this.setError('An error occured to get the data');
    }
  }
}

My test is the following:

it('getData function should affect the cost and totalSupply to the data', async () => {

window.ethereum = jest.fn();
let ethers = {
    providers: {
        Web3Provider: jest.fn()
    },
    Contract: jest.fn()
}

let contract = {
    cost: jest.fn(),
    totalSupply: jest.fn()
};

const costMocked = 5;
const totalSupplyMocked = 50;
contract.cost.mockResolvedValue(costMocked);
contract.totalSupply.mockResolvedValue(totalSupplyMocked);

await wrapper.vm.getData();

expect(wrapper.vm.data.cost).toBe('5');
expect(wrapper.vm.data.totalSupply).toBe('50');

  });

The test enters into the 'try' but stop at await contract.cost(); and catch the error: could not detect network

How to mock a network windows.ethereum/provider/contract from the library ethers?

CodePudding user response：

I found a solution: I'm using eth-testing package to mock the provider and contract interaction:

it('getData function should affect the cost and totalSupply to the data', async () => {

    // Start with not connected wallet
    testingUtils.mockNotConnectedWallet();
    // Mock the connection request of MetaMask
    testingUtils.mockRequestAccounts(["0xe14d2f7105f759a100eab6559282083e0d5760ff"]);
    //allows to mock the chain ID / network to which the provider is connected --> 0x3 Ropsten network
    testingUtils.mockChainId("0x3");

    const abi = NftContract.abi;
    // An address may be optionally given as second argument, advised in case of multiple similar contracts
    const contractTestingUtils = testingUtils.generateContractUtils(abi);

    await contractTestingUtils.mockCall("cost", [5]);
    await contractTestingUtils.mockCall("totalSupply", [50]);

    await wrapper.vm.getData();

    expect(wrapper.vm.data.cost).toBe('5');
    expect(wrapper.vm.data.totalSupply).toBe('50');
  });