test: add unit tests for DashboardHeader component

[srinidhi-2006-bit]

Summary

Adds comprehensive unit tests for the DashboardHeader component using Vitest and React Testing Library. These tests improve coverage for rendering, session-based behavior, profile visibility, API interactions, and error handling.

Closes #1042

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Type of Change

• 🧪 Tests only

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What Changed

• Added additional unit tests in test/components/DashboardHeader.test.tsx
• Added test coverage for authenticated and unauthenticated user states
• Added tests for public/private profile visibility and settings fetch behavior
• Added error handling test cases for failed API requests
• Verified DashboardHeader rendering and key UI elements

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How to Test

1. Install dependencies:

   npm install

2. Run the DashboardHeader test suite:

   npx vitest test/components/DashboardHeader.test.tsx

3. Verify all tests pass successfully.

Expected result:

All DashboardHeader tests pass without failures and component behavior is validated across different session and API states.

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Screenshots / Recordings

Not applicable (tests only).

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Checklist

• Linked the related issue above
• Self-reviewed my own diff
• No unnecessary console.log, debug code, or commented-out blocks
• npm run lint passes locally
• No TypeScript errors introduced by this change
• Added or updated tests where applicable
• Updated documentation / comments if behavior changed (not applicable)

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Accessibility (UI changes only)

Not applicable (tests only).

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Additional Context

The test suite now covers:

• Dashboard heading and overview rendering
• Authenticated vs unauthenticated states
• User settings fetch behavior
• Public profile visibility logic
• Profile URL generation
• Graceful handling of API failures

All tests pass locally using Vitest.

[github-actions]

GSSoC Label Checklist 🏷️

@Umbrella-io — please apply the appropriate labels before merging:

Difficulty (pick one):

• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

Quality (optional):

• quality:clean — ×1.2 multiplier
• quality:exceptional — ×1.5 multiplier

Validation (required to score):

• gssoc:approved — counts for points
• gssoc:invalid / gssoc:spam / gssoc:ai-slop — does not score

Type labels (type:*) are auto-detected from files and title. Review and adjust if needed.
Points formula: (difficulty × quality_multiplier) + type_bonus

[srinidhi-2006-bit]

All component tests, linting, type checks, and coverage checks are passing successfully.

The remaining failure appears to be in the Playwright E2E workflow and may be unrelated to the DashboardHeader unit test changes introduced in this PR. Happy to investigate further if maintainers identify a specific issue connected to these changes.