[FSSDK-12089] run tests in browser using vitest

[raju-opti]

Summary

• This PR configures running unit tests in browser using vitest. Tests can be run on browsers on local machine or on browserstack. A workflow job has been also added to run tests during CI runs.

Test plan

• updated tests to work on browser

Issues

• FSSDK-12089

[coveralls]

coverage: 77.745% (-0.007%) from 77.752%
when pulling dce6896 on raju/browser_check
into f3933c0 on master.

[Copilot]

Pull request overview

This PR configures browser-based unit testing using Vitest, enabling tests to run on both local browsers and BrowserStack with support for multiple browser types (Chrome, Firefox, Edge, Safari). A new CI workflow job has been added to automate browser testing.

• Added comprehensive Vitest browser configuration with BrowserStack integration and local browser fallback
• Implemented custom Vitest plugins for request logging and console capture to improve debugging capabilities
• Updated test mocks to be compatible with browser execution environment and refactored mock patterns for better compatibility

Reviewed changes

Copilot reviewed 23 out of 25 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
vitest.browser.config.mts	New browser test configuration with BrowserStack and local browser support
vitest.config.mts	Updated test file pattern to be more specific
vitest/request-logger-plugin.ts	Custom plugin for logging HTTP requests/responses during browser tests
vitest/console-capture-plugin.ts	Custom plugin for capturing and forwarding browser console logs to the test runner
public/console-capture.js	Client-side script for capturing browser console output and sending to server
scripts/run-browser-tests.js	Main orchestration script for running tests across different browser configurations
scripts/patch-vitest-viewport.js	Script to patch Vitest viewport commands for browser compatibility
lib/utils/cache/local_storage_cache.browser.spec.ts	Fixed test to sort keys before comparison for deterministic results
lib/project_config/project_config_manager.ts	Added blank line for readability
lib/project_config/project_config_manager.spec.ts	Updated test to provide error message to reject() call
lib/project_config/config_manager_factory.react_native.spec.ts	Changed async import to sync require for browser compatibility
lib/logging/logger_factory.spec.ts	Expanded mock to explicitly define all exported values for browser mode
lib/event_processor/event_processor_factory.spec.ts	Updated mocks to provide explicit constructor functions for browser compatibility
lib/event_processor/event_processor_factory.react_native.spec.ts	Changed async import to sync require for browser compatibility
lib/event_processor/event_processor_factory.browser.spec.ts	Refactored mocks to avoid importOriginal() which doesn't work in browser mode
lib/event_processor/batch_event_processor.spec.ts	Fixed mock setup and sorting logic for deterministic test behavior
lib/core/decision_service/index.ts	Made bucketer import path explicit with /index suffix
lib/core/decision_service/index.spec.ts	Refactored bucketer mock to use spy mode instead of hoisted mock
lib/core/bucketer/index.spec.ts	Updated mock pattern to use spy mode with proper MockInstance types
lib/core/audience_evaluator/index.spec.ts	Updated mock pattern to use spy mode with proper MockInstance types
lib/shared_types.ts	Changed regular imports to type imports for better tree-shaking and clarity
package.json	Added new dependencies for browser testing and updated nise version
.gitignore	Added .env to ignore list
.github/workflows/javascript.yml	Added browser_tests job to CI workflow with matrix strategy for multiple browsers

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[Copilot]

The reformatting of the export statement spreads multiple exports across a single line with inconsistent style. This reduces readability. Consider either keeping one export per line or using a more consistent multi-line format with proper indentation.

Suggested change

	OdpManager, OdpSegmentApiManager,
	OdpSegmentManager, OptimizelySegmentOption, RequestHandler
	OdpManager,
	OdpSegmentApiManager,
	OdpSegmentManager,
	OptimizelySegmentOption,
	RequestHandler

[Copilot]

Typo in comment: "vesion" should be "version".

Suggested change

	// vesion should be pinned in package.json devDependencies to avoid
	// version should be pinned in package.json devDependencies to avoid

[Copilot]

Typo in comment: "speicfied" should be "specified".

Suggested change

	it('should return decision response with variation null when a user is bucketed into a different grouped experiment than the one speicfied', () => {
	it('should return decision response with variation null when a user is bucketed into a different grouped experiment than the one specified', () => {

[junaed-optimizely]

Thanks for putting this together. Looks solid overall.