chore(toolkit): trim whitespace from IoMessages (#33284)

### Reason for this change

After removing emojis and ANSI colors, an IoMessage might end up with floating whitespace at either end. We want to trim this whitespace.

### Description of changes

Always trim whitespace from IoMessages.

### Describe any new or updated permissions being added

n/a

### Description of how you validated changes

unit tests

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/toolkit/lib/api/io/private/logger.ts

@@ -79,6 +79,28 @@ function stripEmojis(msg: string): string {
   return msg.replace(/\p{Emoji_Presentation}/gu, '');
 }
 
+/**
+ * An IoHost wrapper that trims whitespace at the beginning and end of messages.
+ * This is required, since after removing emojis and ANSI colors,
+ * we might end up with floating whitespace at either end.
+ */
+export function withTrimmedWhitespace(ioHost: IIoHost): IIoHost {
+  return {
+    notify: async <T>(msg: IoMessage<T>) => {
+      await ioHost.notify({
+        ...msg,
+        message: msg.message.trim(),
+      });
+    },
+    requestResponse: async <T, U>(msg: IoRequest<T, U>) => {
+      return ioHost.requestResponse({
+        ...msg,
+        message: msg.message.trim(),
+      });
+    },
+  };
+}
+
 // @todo these cannot be awaited WTF
 export function asSdkLogger(ioHost: IIoHost, action: ToolkitAction): Logger {
   return new class implements Logger {

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

@@ -19,7 +19,7 @@ import { CachedCloudAssemblySource, IdentityCloudAssemblySource, StackAssembly,
 import { ALL_STACKS, CloudAssemblySourceBuilder } from '../api/cloud-assembly/private';
 import { ToolkitError } from '../api/errors';
 import { IIoHost, IoMessageCode, IoMessageLevel } from '../api/io';
-import { asSdkLogger, withAction, Timer, confirm, error, highlight, info, success, warn, ActionAwareIoHost, debug, result, withoutEmojis, withoutColor } from '../api/io/private';
+import { asSdkLogger, withAction, Timer, confirm, error, highlight, info, success, warn, ActionAwareIoHost, debug, result, withoutEmojis, withoutColor, withTrimmedWhitespace } from '../api/io/private';
 
 /**
  * The current action being performed by the CLI. 'none' represents the absence of an action.
@@ -115,7 +115,9 @@ export class Toolkit extends CloudAssemblySourceBuilder implements AsyncDisposab
     if (props.color === false) {
       ioHost = withoutColor(ioHost);
     }
-    this.ioHost = ioHost;
+    // After removing emojis and color, we might end up with floating whitespace at either end of the message
+    // This also removes newlines that we currently emit for CLI backwards compatibility.
+    this.ioHost = withTrimmedWhitespace(ioHost);
   }
 
   public async dispose(): Promise<void> {

packages/@aws-cdk/toolkit/test/toolkit/toolkit.test.ts

@@ -9,42 +9,64 @@ import * as chalk from 'chalk';
 import { Toolkit } from '../../lib';
 import { TestIoHost } from '../_helpers';
 
-test('emojis can be stripped from message', async () => {
-  const ioHost = new TestIoHost();
-  const toolkit = new Toolkit({ ioHost, emojis: false });
-
-  await toolkit.ioHost.notify({
-    message: '💯Smile123😀',
-    action: 'deploy',
-    level: 'info',
-    code: 'CDK_TOOLKIT_I0000',
-    time: new Date(),
+describe('message formatting', () => {
+  test('emojis can be stripped from message', async () => {
+    const ioHost = new TestIoHost();
+    const toolkit = new Toolkit({ ioHost, emojis: false });
+
+    await toolkit.ioHost.notify({
+      message: '💯Smile123😀',
+      action: 'deploy',
+      level: 'info',
+      code: 'CDK_TOOLKIT_I0000',
+      time: new Date(),
+    });
+
+    expect(ioHost.notifySpy).toHaveBeenCalledWith(expect.objectContaining({
+      action: 'deploy',
+      level: 'info',
+      code: 'CDK_TOOLKIT_I0000',
+      message: 'Smile123',
+    }));
   });
 
-  expect(ioHost.notifySpy).toHaveBeenCalledWith(expect.objectContaining({
-    action: 'deploy',
-    level: 'info',
-    code: 'CDK_TOOLKIT_I0000',
-    message: 'Smile123',
-  }));
-});
+  test('color can be stripped from message', async () => {
+    const ioHost = new TestIoHost();
+    const toolkit = new Toolkit({ ioHost, color: false });
 
-test('color can be stripped from message', async () => {
-  const ioHost = new TestIoHost();
-  const toolkit = new Toolkit({ ioHost, color: false });
+    await toolkit.ioHost.notify({
+      message: chalk.red('RED') + chalk.bold('BOLD') + chalk.blue('BLUE'),
+      action: 'deploy',
+      level: 'info',
+      code: 'CDK_TOOLKIT_I0000',
+      time: new Date(),
+    });
 
-  await toolkit.ioHost.notify({
-    message: chalk.red('RED') + chalk.bold('BOLD') + chalk.blue('BLUE'),
-    action: 'deploy',
-    level: 'info',
-    code: 'CDK_TOOLKIT_I0000',
-    time: new Date(),
+    expect(ioHost.notifySpy).toHaveBeenCalledWith(expect.objectContaining({
+      action: 'deploy',
+      level: 'info',
+      code: 'CDK_TOOLKIT_I0000',
+      message: 'REDBOLDBLUE',
+    }));
   });
 
-  expect(ioHost.notifySpy).toHaveBeenCalledWith(expect.objectContaining({
-    action: 'deploy',
-    level: 'info',
-    code: 'CDK_TOOLKIT_I0000',
-    message: 'REDBOLDBLUE',
-  }));
+  test('whitespace is always trimmed from a message', async () => {
+    const ioHost = new TestIoHost();
+    const toolkit = new Toolkit({ ioHost, color: false });
+
+    await toolkit.ioHost.notify({
+      message: '   test message\n\n',
+      action: 'deploy',
+      level: 'info',
+      code: 'CDK_TOOLKIT_I0000',
+      time: new Date(),
+    });
+
+    expect(ioHost.notifySpy).toHaveBeenCalledWith(expect.objectContaining({
+      action: 'deploy',
+      level: 'info',
+      code: 'CDK_TOOLKIT_I0000',
+      message: 'test message',
+    }));
+  });
 });