Balance of contract

Question

I am testing a smart contract but I have troubles accessing the balance of the contract in my javascript test file. For simplicity assume this is my smart contract:

contract Donation{
  function donate() external payable{}

  function getBalance() external view returns(uint)
  {
    return address(this).balance;
  }
}

In remix I called the donate() function with value = 1 ether, and afterwards when I called the getBalance() function it returned the correct value for the balance.

However, when I use Ganache in combination with javascript I only get 0 as value for the balance of the contract. This is how my test looks like:

it( 'Test contract', async() => {
  instance = await Donation.deployed();

  let balance = await web3.eth.getBalance(instance.address);
  console.log("balance = ", balance);

  user1 = accounts[0];
  instance.donate({value:400000000});

  balance = await web3.eth.getBalance(instance.address);
  console.log("balance = ", balance);
});

The first console.log returns 0 as balance for the smart contract which is fine. However, after calling the donate() function with a value of 400000000, I expected the second console.log() to return that value as the balance of the contract.

I have no idea why the donate() function doesn't increase the contract balance. Anyone has any idea what is wrong here ?

Answer 1

You just need to replace instance.donate({value:400000000}); by await instance.donate({value:400000000}); to get the desired behavior.

Indeed, always use await in your asynchronous tests for each transaction to be sure that they are executed in the correct order.