text: const HelloWorld = artifacts.require('HelloWorld')
  
  // in each contract test, contract gets deployed with a clean state
  // accounts parameter points to Truffle's default 10 dummy accounts. 
  contract('HelloWorld', accounts => {
      it('should get message', async () => {
          // create a deployed contract instance
          let instance = await HelloWorld.deployed()
          let message = await instance.message() // note that state variable is called as method here
          assert.equal(message, 'hello world constructor')
      })
      
      it('owner should be accounts[0]', async () => {
          // create a deployed contract instance
          let instance = await HelloWorld.deployed()
          let owner = await instance.owner() // note that state variable is called as method here
          assert.equal(owner, accounts[0])
      })
      
      it('should return 1 ether', async () => {
          let instance = await HelloWorld.deployed()
          // web3 is available in Truffle
          assert.equal(web3.utils.fromWei('1000000000000000000', 'ether'), '1')
      })
  })