Developing our own Blockchain network for testing solidity contracts using Brownie (Mainnet forking with Alchemy & Infura)

Mainnet is the term used to describe when a blockchain protocol is fully developed and deployed, meaning that cryptocurrency transactions are being broadcasted, verified, and recorded on a distributed ledger technology (blockchain).

In contrast to mainnet networks, the term testnet describes when a blockchain protocol or network is not yet up and running on its full capacity. A testnet is used by programmers and developers to test and troubleshoot all the aspects and features of a blockchain network before they are sure the system is secure and ready for the mainnet launch.

In other words, a testnet only exists as a working prototype for a blockchain project, while a mainnet is a completely developed blockchain platform for users to send and receive cryptocurrency transactions (or any other kind of digital data that is recorded on a distributed ledger)
~Obasi Ifegwu

Procedure:

1. First, let's see existing networks in Brownie using the following command:

brownie networks list

Image showing some existing networks in Brownie

2. I want to name my new network mainnet-fork but wait, there is already one with the same name. mainnet-forkis actually a built-in network in Brownie. So let’s delete it, because why not!

# to delete existing network
brownie networks delete mainnet-fork

Great! isn’t it? By the way, for surety purposes, you can rerun the above command to have a look at existing networks.

3. We can use Infura or Alchemy for forking.

* Alchemy:

• First, go to alchemy.com and log in or signup(in case you haven’t).

• Create a New App with the following settings.

• Open forkingDemo and click on view key and copy the one under HTTP (first one)

• Execute the following command in VSCode terminal( ctrl+` )

# following command
brownie networks add development mainnet-fork cmd=ganache-cli host=http://127.0.0.1 fork=[paste copied key here] accounts=10 mnemonic=brownie port=8545

• The output should be the following:

* Infura:

• First, go to infura.io and sign in.
• Open Dashboard > Create New Project
• Product > Ethereum and Create

• Open your project, go to project settings. It will look something like this:

• Copy that https linkunder ENDPOINTS.
• Execute the following command in VSCode terminal( ctrl+` )

# following command
brownie networks add development mainnet-fork cmd=ganache-cli host=http://127.0.0.1 fork=[paste copied key here] accounts=10 mnemonic=brownie port=8545

3. Testing:

For testing with mainnet-fork use:

brownie test --network mainnet-fork

& the END!

Congrats!!! You have done it. Happy testing xD