Getting async/await to work in truffle JS tests

Question

I see many examples are happily using async/await in their JS tests, but it looks like mine doesn't seem to be using ES8? I'm not sure how to check.

I installed truffle using "npm install truffle" yesterday.

tests/MyToken.js:

...

beforeEach(async function() {
  instance = await MyToken.new();
});

...

Test output:

$ truffle test
Using network 'development'.

/Users/.../truffle/test/MyToken.js:13
  beforeEach(async function() {
             ^^^^^

SyntaxError: missing ) after argument list
    at createScript (vm.js:56:10)
    at Object.runInThisContext (vm.js:97:10)
    at Module._compile (module.js:542:28)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at /Users/.../node_modules/mocha/lib/mocha.js:231:27

Answer 1

I figured it out after deciding to post additional details with the versions of truffle and node.

$ node --version
v6.11.5
$ truffle test
// no support for async

... install the latest node.

$ node --version
v8.9.0
$ truffle test
// async now works :D

Answer 2

With node 8, async/await was enabled by default. Prior to version 7.6 you could use async/await as long as you added the --harmony-async-await flag. For version prior you could also use Babel to transpile down to ES5 compatible javascript. I suggest installing Node 8 or above .

Node ≥ 7.6 confirm by entering node -v in a command line npm ≥ 4 confirm by entering npm -v in command line Truffle ≥ 3.3 confirm by entering truffle -v in command line Ganache-cli ≥ 5.0.0 confirm by entering ganache-cli -v in command line