fix(toolkit): fix broken confirmation prompt (#2333)

We recently upgraded to a 'promptly' version whose methods
are already async, so no need to util.promisify it anymore.
In fact, the promise would never be resolved.

Author: rix0rrr

packages/aws-cdk/bin/cdk.ts

@@ -3,7 +3,6 @@ import 'source-map-support/register';
 
 import colors = require('colors/safe');
 import fs = require('fs-extra');
-import util = require('util');
 import yargs = require('yargs');
 
 import { bootstrapEnvironment, destroyStack, SDK } from '../lib';
@@ -25,7 +24,6 @@ import { VERSION } from '../lib/version';
 
 // tslint:disable-next-line:no-var-requires
 const promptly = require('promptly');
-const confirm = util.promisify(promptly.confirm);
 
 // tslint:disable:no-shadowed-variable max-line-length
 async function parseCommandLineArguments() {
@@ -359,7 +357,7 @@ async function initCommandLine() {
 
     if (!force) {
       // tslint:disable-next-line:max-line-length
-      const confirmed = await confirm(`Are you sure you want to delete: ${colors.blue(stacks.map(s => s.name).join(', '))} (y/n)?`);
+      const confirmed = await promptly.confirm(`Are you sure you want to delete: ${colors.blue(stacks.map(s => s.name).join(', '))} (y/n)?`);
       if (!confirmed) {
         return;
       }

packages/aws-cdk/lib/cdk-toolkit.ts

@@ -1,6 +1,6 @@
 import colors = require('colors/safe');
 import fs = require('fs-extra');
-import { format, promisify } from 'util';
+import { format } from 'util';
 import { AppStacks, ExtendedStackSelection } from "./api/cxapp/stacks";
 import { IDeploymentTarget } from './api/deployment-target';
 import { printSecurityDiff, printStackDiff, RequireApproval } from './diff';
@@ -9,7 +9,6 @@ import { deserializeStructure } from './serialize';
 
 // tslint:disable-next-line:no-var-requires
 const promptly = require('promptly');
-const confirm = promisify(promptly.confirm);
 
 export interface CdkToolkitProps {
   /**
@@ -98,7 +97,7 @@ export class CdkToolkit {
               'but terminal (TTY) is not attached so we are unable to get a confirmation from the user');
           }
 
-          const confirmed = await confirm(`Do you wish to deploy these changes (y/n)?`);
+          const confirmed = await promptly.confirm(`Do you wish to deploy these changes (y/n)?`);
           if (!confirmed) { throw new Error('Aborted by user'); }
         }
       }
@@ -230,4 +229,4 @@ export interface DeployOptions {
    * Reuse the assets with the given asset IDs
    */
   reuseAssets?: string[];
-}
+}