Add comprehensive unit tests for Login component

[devin-ai-integration]

Add comprehensive unit tests for Login component

Summary

This PR introduces a complete testing infrastructure for the component library and adds comprehensive unit tests for the Login component. The implementation includes Jest and React Testing Library setup, achieving 100% statement coverage and 93.18% branch coverage across 37 test cases.

Key Changes:

• Set up Jest testing framework with React Testing Library
• Added Babel configuration for JSX transformation
• Created comprehensive test suite covering all Login component functionality
• Added test scripts for development workflow (npm test, npm run test:watch, npm run test:coverage)

Testing Coverage:

• Form validation and user interactions (email, password, checkbox)
• Conditional rendering (logo, error messages, social logins, create account)
• Button states (enabled/disabled, loading states)
• Social login functionality with different providers
• Accessibility attributes and ARIA compliance
• Edge cases (whitespace validation, missing props)

Review & Testing Checklist for Human

• Verify tests validate user behavior, not implementation: Review test cases to ensure they test what users actually do (clicking buttons, typing in forms) rather than internal component state
• Run tests locally in your environment: Execute npm test and npm run test:coverage to verify the testing setup works outside of the development environment
• Test Login component in actual application: Import and use the Login component in a consuming app (browse-app, vg-browse, or my-account-app) to verify tests match real-world behavior
• Verify build process still works: Run npm run build and confirm the component library still builds correctly with new dependencies
• Check test scenarios match requirements: Review the 37 test cases against the actual Login component requirements to identify any missing or incorrect test scenarios

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    LoginComponent["src/components/Login/<br/>Login.js"]:::context
    LoginCSS["src/components/Login/<br/>Login.css"]:::context
    LoginIndex["src/components/Login/<br/>index.js"]:::context
    
    TestFile["src/components/Login/<br/>__tests__/Login.test.js"]:::major-edit
    PackageJSON["package.json"]:::major-edit
    BabelRC[".babelrc"]:::major-edit
    SetupTests["src/setupTests.js"]:::major-edit
    
    TestFile -->|"tests all props<br/>and behaviors"| LoginComponent
    TestFile -->|"imports and renders"| LoginIndex
    BabelRC -->|"transforms JSX"| TestFile
    SetupTests -->|"configures testing<br/>environment"| TestFile
    PackageJSON -->|"defines Jest config<br/>and test scripts"| TestFile
    
    subgraph Legend
        L1[Major Edit]:::major-edit
        L2[Minor Edit]:::minor-edit  
        L3[Context/No Edit]:::context
    end

    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• This is the first testing infrastructure added to the component library, establishing patterns for future component testing
• The test coverage metrics (100% statements, 93.18% branches) are encouraging but should be validated against real usage
• All existing functionality remains unchanged - this is purely additive testing infrastructure
• The testing setup follows React ecosystem best practices with Jest + React Testing Library

Link to Devin run: https://app.devin.ai/sessions/ca135997aa11410ab0e8c106bd2d1fdc
Requested by: @ben-windsurf (ben.lehrburger@windsurf.com)

[devin-ai-integration]

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