Solidity – How to Set Maximum Block Gas in Ganache-CLI

Using Truffle and testrpc. It's actually pretty easy to build a development environment and test different use cases.

For the gas estimation, it's mostly based on Web3 native functions:

1. You can retrieve the gas price (in wei) using web3.eth.getGasPrice

2. The function estimateGas will give the gas estimation for a function (with the parameters passed)

3. Multiply number of gas by gas price to get the gas cost estimation.

For example

var TestContract = artifacts.require("./Test.sol");

// Run unit tests to populate my contract
// ...
// ...

// getGasPrice returns the gas price on the current network
TestContract.web3.eth.getGasPrice(function(error, result){ 
    var gasPrice = Number(result);
    console.log("Gas Price is " + gasPrice + " wei"); // "10000000000000"

    // Get Contract instance
    TestContract.deployed().then(function(instance) {

        // Use the keyword 'estimateGas' after the function name to get the gas estimation for this particular function 
        return instance.giveAwayDividend.estimateGas(1);

    }).then(function(result) {
        var gas = Number(result);

        console.log("gas estimation = " + gas + " units");
        console.log("gas cost estimation = " + (gas * gasPrice) + " wei");
        console.log("gas cost estimation = " + TestContract.web3.fromWei((gas * gasPrice), 'ether') + " ether");
    });
});

Result in my case (private network):

> truffle test
Using network 'test'.

Compiling .\contracts\Migrations.sol...
Compiling .\contracts\Test.sol...

Gas Price is 20000000000 wei
gas estimation = 26794 units
gas cost estimation = 535880000000000 wei
gas cost estimation = 0.00053588 ether

I think you may be alluding to the online remix compiler for Solidity. This will allow you to see easily how much gas a transaction to a function will need/spent.

If you execute a state changing function then inspect the details of the transaction you'll get more information. Please see the example below:

Here we can see trasaction cost & execution cost. Everything you need. Hope this helps.