Building software requires you to test before you release. The usual development process goes from running things on your local computer, to running it on a test system, to running it on the production system.
This process also holds true for Web3 development. You install a local blockchain network on your own machine to test the basic functionality of your smart contracts and later you deploy the system onto a test network, to make sure it still works togeher with many other smart contracts you might use in your application.
Test networks enable testing on real infrastructure without spending real tokens, and in turn, real money. A TX on the Ethereum network can easily cost $10, so when you're just testing and sending hundreds of TXS a day, this can get costly quick! With free test tokens that's not an issue anymore.
Also, if you accidentally push a development key to a public repository, you won't lose anything but the worthless test tokens you put on that address.
This is why you had to copy a private key in the previous lesson. You need an address you can reuse so you can get tokens on it and spend them for gas or to do transactions that require payment.
Note: We will go into the details of gas costs later. This lesson is just about connecting to a test network and getting our first tokens!
In Part I of this course, you learned how to use providers to connect to a blockchain network. You
simply called the ethers.getDefaultProvider method and got a provider to read data
from the chain.
The default provider connects, by default, to the Ethereum main network. Which is the production
environment of Ethereum. If you want to connect to a test network, you have to use the first
parameter of that method. In our case it will be "goerli".
Note: Görli is one of Ethereum test networks, Ethers.js knows about it, so we can simply use the name. For other networks that are compatible with Ethers.js, you need more configuration.
The code is similar to the last lesson, but this time, I want you to call getChainId
to ensure you're connected to the test network. The correct ID is 5.
const wallet = new ethers.Wallet( "0x350690562a6c31051d2c9f085e0b91be0a4ac0a3c206998c89ff3cfedf3524d0" ) const provider = ethers.getDefaultProvider("goerli") const connectedWallet = wallet.connect(provider) const chainId = await connectedWallet.getChainId() print(chainId)
Now that you know how to connect to a test network, we will go back to the question why I asked you to copy a private key and address.
On blockchain networks you have to pay for writing actions, which means sending transactions. If you send an TX from an address that doesn't own enough of the networks native token, your TX won't get executed. So, if you create random private keys for development all the time, they will never have any tokens to pay for anything.
To fix this, you create one or more private key for development, load them up with tokens, and use them to pay for your TXS. While you have to buy tokens on the main network, you can get them for free from a token faucet.
A faucet is a website, where you enter the address of your development account, and it will send you test network tokens for free.
Choose one of the following faucets to request test tokens for the address that belongs to the private key you copied in the last lesson.
If your choosen faucet accepted your request, you want to check out if it worked and you got your tokens. You can do this in multiple ways. One is to go on Etherscan, a blockchain explorer, enter the address you used in the faucet and search for it.
Note: Etherscan is a search engine for addresses. Everything on-chain is public and you can browse it freely.
The second way is to check the balance programmatically with Ethers.js. So, try it yourself.
Connect to the Görli testnet, and call the getBalance method on your wallet. It is
asynchronous and returns a BigNum.
const wallet = new ethers.Wallet( "0x350690562a6c31051d2c9f085e0b91be0a4ac0a3c206998c89ff3cfedf3524d0" ) const provider = ethers.getDefaultProvider("goerli") const connectedWallet = wallet.connect(provider) const balance = await connectedWallet.getBalance() print(`${connectedWallet.address} owns ${ethers.utils.formatEther(balance)} ETH`)
If everything went correctly, the balance of your address should be higher than 0.
In this lesson you learned what tests networks are and how they fit inside your development processes. Main networks are the production environment of blockchain networks, and test networks are, well, the test environments.
You also learned that these test networks come with their own test tokens and how to request them from one of the multiple faucets out there.