test: add NonceProvider coverage for cache creation and memoization

[ovpv]

Summary
This PR adds a new test suite for NonceProvider.tsx to increase confidence in Emotion cache creation and state memoization within the provider. NonceProvider is a small but important utility in the styling pipeline, and previously it had no direct test coverage. The new tests ensure its behaviour is correct, stable, and resilient to future refactors.

Motivation
Because this logic was untested, regressions could slip in unnoticed — especially around memoization behaviour or CSP-related attributes. This PR introduces targeted unit tests to close that gap.

What This PR Does
This PR introduces a new test file:
packages/react-select/src/__tests__/NonceProvider.test.tsx

The test suite covers:

1. ✔ Correct cache creation
   Ensures createCache is called with the expected { key, nonce } values.

2. ✔ Correct rendering of children
   Verifies that the provider passes through its children as expected.

3. ✔ Cache memoization across stable props
   When nonce and cacheKey remain the same across rerenders:

• The Emotion cache is not recreated
• The same cache instance (identified via injected test id) persists

4. ✔ Cache recreation when props change
   If nonce or cacheKey changes:

• A new Emotion cache instance is created
• The previous instance is not reused

5. ✔ Proper integration with Emotion’s CacheProvider
   Using a lightweight mock of CacheProvider, tests validate that:

• The generated cache is passed through
• key, nonce, and a test id propagate correctly

Testing Approach

• @emotion/cache is mocked to prevent side effects and control cache instances deterministically.
• CacheProvider is mocked to expose internal props via data-* attributes, allowing the tests to assert behaviour without inspecting DOM style tags.
• No changes were made to core library logic — this is a test-only addition.

Impact

• Increases coverage for an untested but important component.
• Reduces risk of regressions when future Emotion or CSP-related updates occur.
• No runtime or bundle changes.
• No breaking changes.

[changeset-bot]

🦋 Changeset detected

Latest commit: e8fdf3f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
react-select	Patch

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[ovpv]

not sure why circleci pipeline is failing

please let me know if i need to do anything about this

[ovpv]

not sure why circleci pipeline is failing

please let me know if i need to do anything about this

AI to the rescue, found the prettier issue and fixed it :)