Jest: Unexpected token "function"

[DuncanBetts]

Comments welcome, but I intend on working on this myself.

Travis CI Failure:

FAIL  src/components/Home/Hero/ExchangeWidget/ExchangeWidget.test.js
  ● Test suite failed to run
    Jest encountered an unexpected token
    This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript.
    By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".
    Here's what you can do:
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.
    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/en/configuration.html
    Details:
    /home/travis/build/onitsoft/nexchange-open-client-react/node_modules/await-transaction-mined/index.js:8
        var transactionReceiptAsync = async function(txnHash, resolve, reject) {
                                            ^^^^^^^^
    SyntaxError: Unexpected token function
      at ScriptTransformer._transformAndBuildScript (node_modules/jest-runtime/build/script_transformer.js:403:17)
      at Object.<anonymous> (node_modules/@colony/purser-metamask/staticMethods.js:20:30)
      at Object.<anonymous> (node_modules/@colony/purser-metamask/class.js:34:22)

This issue suggests amending the babelrc to use babel-preset-env "which keeps up to date with the latest language features" - currently the babelrc only includes react-app.