With reference to OpenZeppelin/openzeppelin-contracts#584 (comment) , here is the working code. Thanks https://github.com/Shrugs
it('Token transfer', async () => {
const fromAccount = accounts[1]
const toAccount = accounts[4]
const transferLimit = 4000000000000000000
const transferAmount = 3000000000000000000
let ecoSystemBalance = await tokenInstance.balanceOf(fromAccount)
assert.isAtLeast(ecoSystemBalance, transferLimit, 'From account balance should be atleast 4')