var scope = typeof window === 'undefined' ? global : window scope.hasWarned = function (_, msg) { var count = _.warn.calls.count() while (count--) { var args = _.warn.calls.argsFor(count) if (args.some(containsMsg)) { return true } } console.warn('[test] "' + msg + '" was never warned.') function containsMsg (arg) { return arg.indexOf(msg) > -1 } } scope.process = { env: { NODE_ENV: 'development' } }