Add comprehensive unit tests for FeedComponent in COG-GTM/angular2-hn

[devin-ai-integration]

Summary

This PR adds a new test file src/app/feeds/feed/feed.component.spec.ts with 40+ unit tests covering the FeedComponent. The tests use Jasmine/Karma with Angular's TestBed and mock the HackerNewsAPIService and ActivatedRoute dependencies.

Test coverage includes:

• Component initialization and default values
• Routing parameter handling and pagination logic (listStart calculation)
• API integration (fetchFeed calls, success/error handling)
• All 5 feed types (news, newest, show, ask, jobs)
• Template rendering (loader, error message, items, job header)
• Navigation links (prev/more visibility and routerLinks)
• Window scroll behavior on page load/navigation
• Edge cases (page 0, large page numbers, non-numeric params)

Review & Testing Checklist for Human

• Run tests locally (npm test) - Tests compiled successfully but could not be executed in the dev environment due to ChromeHeadless unavailability. This is the most critical verification needed.
• Verify edge case tests document expected behavior - The tests for page 0 (listStart=-29) and non-numeric page params (pageNum=NaN) document current component behavior which may actually be bugs worth fixing separately.
• Check subscription cleanup - The component has typeSub and pageSub subscriptions but no ngOnDestroy to unsubscribe. Consider if this is a memory leak that should be addressed.

Recommended test plan:

1. Run npm test and verify all 40+ tests pass
2. Check code coverage report to confirm FeedComponent coverage improved

Notes

• The MockItemComponent uses selector: 'item' to match the actual component (which doesn't follow Angular naming conventions), requiring a tslint disable comment
• Pre-existing lint errors in other files were not modified

Link to Devin run: https://app.devin.ai/sessions/25eb34317eb54f8ebe15573d735f5a71
Requested by: mason.batchelor@cognition.ai (@mbatchelor81)

[devin-ai-integration]

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