[linglingye001]

Adds Node.js live-service integration tests to verify provider behavior against the dedicated appconfig-jsprovider-integrationtest store.

Coverage:

• Loading key values/feature flags with selectors.
• Parsing JSON values and constructing hierarchical configuration objects.
• Refreshing key values/feature flags after updates, additions, and deletions.
• Refreshing only when the watched sentinel’s label changes.

Test infrastructure

• Adds npm run test:integration, compiling ESM tests and running them serially with Mocha/Chai.
• Uses DefaultAzureCredential for authentication and the SDK to manage fixtures.
• Isolates each test with a unique prefix and cleans up only its tracked keys and labels.

[Copilot]

🟢 Approval recommended

Static review found no blocking issues in the test-only changes, fixture isolation, cleanup, or execution command.

No open issues 🎉

What changed in this PR

Adds live-service integration coverage for the JavaScript provider against the dedicated App Configuration test store, without changing production code.

Changes:

• Covers selector-based loading, JSON parsing, hierarchical configuration, and key-value and feature-flag refresh.
• Adds isolated fixtures with tracked cleanup, refresh polling, response tracking, and helper unit tests.
• Adds a serial ESM integration-test command using DefaultAzureCredential authentication.

File	Description
test/​integrationHelpers.test.ts	Tests fixture isolation, cleanup, polling, and response tracking.
test/​integration/​refresh.test.ts	Tests collection refresh and label-specific sentinel monitoring.
test/​integration/​load.test.ts	Tests loading values with key and label selectors.
test/​integration/​json.test.ts	Tests JSON parsing and hierarchical configuration construction.
test/​integration/​helpers.ts	Provides isolated fixtures, cleanup, polling, and response tracking.
test/​integration/​featureFlag.test.ts	Tests feature-flag selection and independent refresh.
package.json	Adds the serial integration-test command.

_{Review effort: Balanced}