Truffle test calling another contract in a smart contract

[EmmanuelTom]

`const Token = artifacts.require("MyToken");
const TokenSale = artifacts.require("MyTokenSale");

contract("TokenSale", async function(accounts) {
const [ initialHolder, recipient, anotherAccount ] = accounts;

it("all coins should be in the tokensale smart contract", async () => {
    let instance = await Token.deployed();
    `let balance = await instance.balanceOf.call(TokenSale.address);`
    let totalSupply = await instance.totalSupply.call();
    return expect(balance).to.be.a.bignumber.equal(totalSupply);
});	

}); `

This code is actually from a course Im taking, they is something I don't really understand here:
In the code the Token and TokenSale are different smart contracts then from the test why did we let instance = await Token.deployed(); to check for the balance of TokenSale contract by doing let balance = await instance.balanceOf.call(TokenSale.address);?

Can't we just use the instance of TokenSale ?