In a crowdsale contract, the buyer calls the buyTokens() function, and sends ether along to receive tokens in exchange. In the openzeppelin contracts, the buyToken takes only parameter - address _beneficiary.

I am faced with a problem & a challenge
1] Problem- How will a user send ether to this function? For eg: CrowdSale.address.call{value: _weiAmount}, or just call the buyTokens function.

2] How can i test this function in a local environment[truffle, or ganache]?


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CODE BLOCK
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function buyTokens(address _beneficiary) public payable {
_beneficiary = msg.sender;
uint256 _weiAmount = msg.value;
uint256 _numberOfTokenUnits = _weiAmount.div(_rate);

_prePurchaseCheck(_beneficiary, _weiAmount);

_processPurchase(_beneficiary, _numberOfTokenUnits);
tokenSold = tokenSold.add(_numberOfTokenUnits);
_weiRaised = _weiRaised.add(_weiAmount);

_forwardFunds(_weiAmount);

emit TokensPurchased(_beneficiary, _beneficiary, _numberOfTokenUnits, block.timestamp);

}

function _prePurchaseCheck(address _buyer, uint256 _amount) internal view {
require(tokenSold <= 6000000000, "Sold out. Wait for phase 2 sale.");
require(_amount >= 500000000000000000 && _amount<= 10000000000000000000, "You can only purchase with amounts between 0.5 ether to 10 ether. Alternatively, the tokens available for sale maybe less than 0.5 ether. ");
require(_buyer != address(0), "Buyer can not be zero address");
}
function _processPurchase(address _beneficiary, uint256 _value) internal {
token.transfer(_beneficiary, _value);
this;
}

function _forwardFunds(uint256 _amount) internal /* returns(bool success) */ {
_wallet.transfer(_amount);
}

@Lauri_P Tagging you for better visibility.