Add unit tests for AiAssistUI class to ensure functionality and reliability of UI components

[me146]

Please ensure the following dependencies are added to the project to prevent errors and maintain consistency across all pull requests:

npm install sinon @ckeditor/ckeditor5-core

This is a common requirement, and including these dependencies in the project setup will avoid the need to include them individually in each pull request.

[jjroelofs]

I installed sinon but get an error message about a missing sinon config file and another failure, please check it out. I recommend using a separate PR or just commit to 1.x with the required file, however if you update packages please use yarn, not npm, and commit changes to the yarn.lock file to ensure we are on the same versions of dependencies.

(base) jur@jurs-MacBook-Pro ckeditor5-ai-assist % yarn run test
yarn run v1.22.22
warning ../package.json: No license field
$ ckeditor5-package-tools test
Entry file saved in "/Users/jur/www/ckeditor5-ai-assist/tmp/tests-entry-point.js".

START:
Webpack bundling...
asset commons.js 6.4 MiB [emitted] (name: commons) (id hint: commons)
asset runtime.js 8.53 KiB [emitted] (name: runtime)
asset tests-entry-point.3893782553.js 1.04 KiB [emitted] (name: tests-entry-point.3893782553)
Entrypoint tests-entry-point.3893782553 6.41 MiB = runtime.js 8.53 KiB commons.js 6.4 MiB tests-entry-point.3893782553.js 1.04 KiB

ERROR in /Users/jur/www/ckeditor5-ai-assist/tests/aiassistui.ts
./tests/aiassistui.ts 6:18-25
[tsl] ERROR in /Users/jur/www/ckeditor5-ai-assist/tests/aiassistui.ts(6,19)
      TS7016: Could not find a declaration file for module 'sinon'. '/Users/jur/www/ckeditor5-ai-assist/node_modules/sinon/pkg/sinon-esm.js' implicitly has an 'any' type.
  Try `npm i --save-dev @types/sinon` if it exists or add a new declaration (.d.ts) file containing `declare module 'sinon';`
ts-loader-default_aadc0d91f92e8c5c
 @ ./tmp/tests-entry-point.js 2:0-64

webpack 5.96.1 compiled with 1 error in 2858 ms
18 11 2024 14:45:00.082:INFO [karma-server]: Karma v6.4.4 server started at http://localhost:9876/
18 11 2024 14:45:00.082:INFO [launcher]: Launching browsers CHROME_LOCAL with concurrency unlimited
18 11 2024 14:45:00.085:INFO [launcher]: Starting browser Chrome
18 11 2024 14:45:00.988:INFO [Chrome 130.0.0.0 (Mac OS 10.15.7)]: Connected on socket 7dp7RiH8-FXgf5LyAAAB with id 82012254
  AiAssist
    ✔ should be named
    init()
      ✖ "before each" hook for "should load AiAssist"
      ✖ "after each" hook for "should load AiAssist"
  AiAssistUI
    ✔ should be loaded
    ✔ should handle inline-slash element correctly
    initializeUIComponents()
      ✔ should register inline-slash schema and conversions
      ✔ should initialize UI components
      ✔ should add aiAssistButton to the toolbar
    attachListener()
      ✔ should attach event listeners to the editor
    PlaceHolder For AI prompt
      ✔ should show placeholder at the specified position
      ✔ should hide placeholder if no position is specified
      ✔ should hide the placeholder element
    AI request loader
      ✔ should show loader at the specified position
      ✔ should hide loader if no position is specified
      ✔ should hide the loader element
LOG: 'Showing error message...', 'Test error message'
    AI request error
      ✔ should show error tooltip with the specified message
      ✔ should hide the error tooltip element
    applyPlaceholderToCurrentLine()
      ✔ should show placeholder for empty lines
      ✔ should hide placeholder for non-empty lines
  CKEditor5 AiAssist DLL
    ✔ exports AiAssist
    icons
      ✔ exports the "ckeditor" icon

Finished in 2.296 secs / 2.034 secs @ 14:45:03 GMT+0100 (Central European Standard Time)

SUMMARY:
✔ 19 tests completed
✖ 2 tests failed

FAILED TESTS:
  AiAssist
    init()
      ✖ "before each" hook for "should load AiAssist"
        Chrome 130.0.0.0 (Mac OS 10.15.7)
      Error: AiAssist: apiKey is required.
          at AiAssist.validateConfiguration (webpack://@dxpr/ckeditor5-ai-assist/./src/aiassist.js?:54:19)
          at new AiAssist (webpack://@dxpr/ckeditor5-ai-assist/./src/aiassist.js?:44:14)
          at eval (webpack://@dxpr/ckeditor5-ai-assist/./node_modules/@ckeditor/ckeditor5-core/src/plugincollection.js?:334:52)
          at Array.map (<anonymous>)
          at loadPlugins (webpack://@dxpr/ckeditor5-ai-assist/./node_modules/@ckeditor/ckeditor5-core/src/plugincollection.js?:332:39)
          at PluginCollection.init (webpack://@dxpr/ckeditor5-ai-assist/./node_modules/@ckeditor/ckeditor5-core/src/plugincollection.js?:161:33)
          at ClassicEditor.initPlugins (webpack://@dxpr/ckeditor5-ai-assist/./node_modules/@ckeditor/ckeditor5-core/src/editor/editor.js?:301:29)
          at eval (webpack://@dxpr/ckeditor5-ai-assist/./node_modules/@ckeditor/ckeditor5-editor-classic/src/classiceditor.js?:173:28)
          at new Promise (<anonymous>)
          at ClassicEditor.create (webpack://@dxpr/ckeditor5-ai-assist/./node_modules/@ckeditor/ckeditor5-editor-classic/src/classiceditor.js?:171:16)

      ✖ "after each" hook for "should load AiAssist"
        Chrome 130.0.0.0 (Mac OS 10.15.7)
      TypeError: Cannot read properties of undefined (reading 'destroy')
          at Context.eval (webpack://@dxpr/ckeditor5-ai-assist/./tests/aiassist.ts?:37:27)

/Users/jur/www/ckeditor5-ai-assist/node_modules/@ckeditor/ckeditor5-package-tools/lib/tasks/test.js:36
				reject( new Error( `Karma finished with "${ exitCode }" code.` ) );
				        ^

Error: Karma finished with "1" code.
    at /Users/jur/www/ckeditor5-ai-assist/node_modules/@ckeditor/ckeditor5-package-tools/lib/tasks/test.js:36:13
    at removeAllListeners (/Users/jur/www/ckeditor5-ai-assist/node_modules/karma/lib/server.js:468:9)
    at Server.<anonymous> (/Users/jur/www/ckeditor5-ai-assist/node_modules/karma/lib/server.js:475:9)
    at Object.onceWrapper (node:events:633:28)
    at Server.emit (node:events:531:35)
    at Server.emit (node:domain:488:12)
    at emitCloseNT (node:net:2376:8)
    at process.processTicksAndRejections (node:internal/process/task_queues:89:21)

Node.js v22.9.0
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
(base) jur@jurs-MacBook-Pro ckeditor5-ai-assist %