How to send tokens to contract address

Question

I want to send erc20 tokens to contract address which is able to trade the token.

However, I failed the test and error says Error: VM Exception while processing transaction: revert

My function is this

TokenSale.sol

  function startSale(address _tokenSaleContractAddress) public {
    require(msg.sender == admin);
    require(tokenContract.transfer(_tokenSaleContractAddress, 750000)); 
  }

MyToken.sol

  function transfer(address _to, uint256 _value) public returns (bool success) {
    require(balanceOf[msg.sender] >= _value);

    balanceOf[msg.sender] -= _value;
    balanceOf[_to] += _value;

    emit Transfer(msg.sender, _to, _value);

    return true;
  }

My test is this

  it('facilitates start sale', function() {
    return MyToken.deployed().then(function(instance) {
      tokenInstance = instance;
      return TokenSale.deployed()
    }).then(function(instance) {
      tokenSaleInstance = instance;
      return tokenSaleInstance.startSale(tokenSaleInstance.address, {from: admin} )
    }).then(function(receipt) {

      return tokenInstance.balanceOf(tokenSaleInstance.address)
    }).then(function(balance) {
      assert.equal(balance.toNumber, 750000);
    });
  });

Could you give me any advise why I failed the test?

Answer 1

Admin has 1000000 tokens, and I want to send 750000 tokens to TokenSale contract.

To do this, the admin needs to call transfer on the token contract. I.e. your test code should have this in it:

tokenInstance.transfer(tokenSaleInstance.address, 750000, { from: admin });

After that, calling startSale should succeed, but there's no reason to call it because it's just transferring 750,000 tokens to itself.