What are the ways of creating contract instance in a client environment, example in test?

Question

I have found this sample from udemy course

https://github.com/acloudfan/Blockchain-Course-Basic-Solidity/blob/93ca256bcf8c436c144425291257dcff5c3b269f/test/TestMetacoin.sol#L10

It uses the DeployedAddress.Metacoin() and pass it to a constructor of the Contract class, what is happening in here? I tried to look and google for ways to create a contract instance but to no luck I am getting an information about this. What I am reading is using deployed() as a way to get the instance, etc specialy during the unit test.

Is this a valid way to create a contract instance using the deployed contract address? Or is all of this just happening locally and not send to a network/node or something?

Answer 1

This code doesn't create nor deploy a contract. It takes the address of the deployed instance and casts to the contract type. MetaCoin meta = MetaCoin(DeployedAddresses.MetaCoin());

DeployedAddresses is a library created after running the migrations scripts (see details here https://github.com/trufflesuite/truffle/blob/develop/packages/resolver/lib/sources/truffle/Deployed.ts#L10-L51). There one function for every deployed contract that returns its address.