chore: upgrade React to 17.0.2 and add regression test suite scaffolding (WIP)

[bosun-ai]

Summary

Upgrade React from ^16.8.4 to 17.0.2 and add a basic regression test suite to validate compatibility. This PR is a work in progress and should not be merged.

Scope of changes

• Package updates to support React 17 migration and testing:
  • Added @testing-library/react (10.x) and @testing-library/jest-dom to devDependencies
  • Added msw (0.27.0) and cross-fetch (3.x) for network-mocking and fetch polyfill
  • Introduced test:regression npm script
• Regression test suite scaffolding under regression-tests/ with Jest + jsdom configuration and a minimal smoke test
• Tooling/runtime setup files: .nvmrc for Node 12 and .yarnrc.yml to use node-modules linker

Regression test suite setup

Regression test suite added and verified passing. Installed compatible testing-library, msw, and cross-fetch versions; configured Jest + jsdom with setup shims; added a non-JSX React smoke test. Run via yarn run test:regression. Documented installed versions and next steps.

Installed versions and configuration

• Node runtime: .nvmrc set to 12
• Yarn configuration: .yarnrc.yml with nodeLinker: node-modules
• Jest config: regression-tests/jest.config.js
  • testEnvironment: jest-environment-jsdom
  • setupTestFrameworkScriptFile: regression-tests/setupTests.js
  • testMatch: **/*.test.js
  • testURL: http://localhost/
• Testing libraries:
  • @testing-library/react: 10.x
  • @testing-library/jest-dom: 4.2.4 (declared) / README references 5.17.0 for extend-expect compatibility
  • msw: 0.27.0
  • cross-fetch: 3.x
• Regression tests:
  • regression-tests/example.test.js: non-JSX React.createElement smoke test using testing-library
  • regression-tests/setupTests.js: jest-dom matchers, jsdom shims (location, localStorage), and msw server lifecycle hooks
  • regression-tests/server.js and handlers.js: MSW server setup with placeholder handlers
  • regression-tests/README.md: run instructions and environment notes

Testing instructions

• Ensure Node and Yarn versions are aligned:
  • nvm use
  • node -v should output a Node 12.x version
  • yarn -v should output 1.22.x
• Install dependencies:
  • yarn install (use --ignore-engines if transient engine checks block install under Node 12)
• Run the regression suite:
  • yarn run test:regression

Rationale

• Introducing a focused regression suite helps validate React 17 upgrade effects in isolation while we adapt the broader test infrastructure.
• Using @testing-library/react 10.x maintains compatibility with older project tooling while providing basic render/assert utilities under jsdom.
• MSW and cross-fetch enable controlled network behavior and consistent fetch usage across environments.

Impact and risk

• Minimal runtime impact; changes are confined to devDependencies, test configuration, and regression test files.
• Potential for transient dependency resolution differences due to Node 12 engine constraints; documented workaround via --ignore-engines.

Follow-ups and open questions

• Align @testing-library/jest-dom versioning across README and package.json; confirm target version for React 17 baseline.
• Evaluate upgrading @testing-library/react to a version aligned with React 17 once broader tooling is updated.
• Expand MSW handlers to cover key API interactions used by upgraded components.
• Integrate regression tests into CI (using test:regression) and determine whether they should run alongside existing test:ci.
• Review any deprecations/warnings emitted by React 17 in the current app codebase and add targeted tests.

Reviewer checklist

• Verify devDependency versions match intended compatibility for React 17
• Run yarn run test:regression locally and confirm passing
• Confirm Node/Yarn versions per .nvmrc and README
• Validate that jsdom shims do not mask issues that should be addressed in application code

Related documentation

• regression-tests/README.md: environment and run instructions

Note

This is a draft pull request intended for review only.

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