test(frontend): Migrate from describe/it to flat test() pattern

[rusackas]

Summary

This PR implements a comprehensive migration strategy to move away from nested describe/it test patterns to flat test() functions, following Kent C. Dodds' "avoid nesting when testing" best practices.

Changes

1. ESLint Rules Enforcement

• Added jest/consistent-test-it rule to enforce test over it
• Added no-restricted-globals rule to error on describe and it usage
• Configured in superset-frontend/src/.eslintrc.json

2. Automated Migrations

• Auto-migrated all it to test: 194 files updated via npm run lint-fix
• Flattened simple describe blocks: 5 files with no hooks or complex setup safely migrated

3. Legacy Code Handling

• Added eslint-disable comments with TODO markers to 243 files containing describe blocks
• Marked 1,080 existing describe blocks with: // eslint-disable-next-line no-restricted-globals -- TODO: Migrate from describe blocks
• This allows existing code to work while preventing new usage

Migration Statistics

• Total test files: 482
• it → test migration: 100% complete (194 files)
• describe blocks removed: 5 files (simple cases without hooks)
• describe blocks with TODOs: 243 files (to be migrated gradually)
• Files with hooks requiring manual migration: 198

Files Successfully Flattened

These files had simple describe blocks without hooks and were safely migrated:

• utils/urlUtils.test.ts
• explore/controlPanels/Separator.test.ts
• components/ErrorMessage/ErrorAlert.test.tsx
• components/ModalTitleWithIcon/ModalTitleWithIcon.test.tsx
• components/MessageToasts/reducers.test.js

Benefits

1. Enforces modern patterns: New tests cannot use describe/it (ESLint error)
2. Preserves functionality: All existing tests continue to work
3. Clear technical debt: TODO markers make legacy patterns visible
4. Gradual migration path: Files can be updated as they're touched
5. Better test readability: Flat structure is easier to understand and maintain

Testing Instructions

1. Run tests to confirm everything still passes:

   npm run test

2. Try adding a new describe block - it should trigger an ESLint error:

   describe('NewComponent', () => {  // ❌ ESLint error
     test('works', () => {});
   });

3. New tests should use flat structure:

   test('NewComponent works', () => {  // ✅ Correct pattern
     // test implementation
   });

Additional Information

This migration follows React Testing Library and Jest best practices. The flat test structure:

• Reduces nesting complexity
• Makes test names more descriptive
• Eliminates confusion about hook scopes
• Improves test maintainability

The TODO markers allow us to track and gradually migrate the remaining describe blocks without breaking existing tests.

🤖 Generated with Claude Code

Co-Authored-By: Claude [email protected]

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