Add comprehensive unit tests for all components, pipes, directives, and interceptors

[devin-ai-integration]

Summary

Adds 24 new unit test files achieving comprehensive test coverage across the entire Angular application. Previously only 6 service test files existed; this PR brings the total to 30 test files with 392 passing tests.

New test coverage includes:

• Components (11): app, auth, header, footer, article-comment, article-list, article-meta, article-preview, favorite-button, follow-button, editor, article page, home page, profile page, profile-articles, profile-favorites, settings, list-errors
• Pipes (2): default-image, markdown
• Directive (1): if-authenticated
• Interceptors (3): api, token, error

Also adds zone.js as a dev dependency (required for Angular TestBed).

Review & Testing Checklist for Human

• Run bun run test --run to verify all 392 tests pass
• Spot-check a few test files for reasonable coverage (e.g., home.component.spec.ts tests routing logic, error.interceptor.spec.ts tests 401 handling)
• Verify no production code was modified (only test files + package.json/bun.lock for zone.js)

Notes

• The attached diff from the user referenced a dark mode toggle (ThemeService), but since ThemeService doesn't exist in the repo yet, those changes were not applied
• The ArticleListComponent mutates config objects passed via @Input() (adds limit/offset to filters). Tests account for this by checking individual properties rather than exact object equality
• All tests follow the existing patterns established in the service spec files (zone.js imports, TestBed setup, vi mocks)

Link to Devin session: https://app.devin.ai/sessions/98d889a1e632485fae587e2692d84169
Requested by: @WesternConcrete

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[devin-ai-integration]

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[devin-ai-integration]

Devin Review found 1 potential issue.

View 6 additional findings in Devin Review.

[devin-ai-integration]

🔴 Angular package version mismatch: @angular/core at 21.2.4 while all other @angular/ packages remain at 21.1.1*

@angular/core was upgraded to 21.2.4 but all other Angular packages (@angular/common, @angular/compiler, @angular/forms, @angular/router, @angular/platform-browser, @angular/platform-browser-dynamic, @angular/compiler-cli, @angular/build, @angular/cli) remain at 21.1.1. Angular uses exact version peer dependencies between its packages — @angular/core@21.2.4 requires @angular/compiler: "21.2.4" (per the lockfile), but only 21.1.1 is installed. Conversely, @angular/common@21.1.1, @angular/forms@21.1.1, @angular/router@21.1.1, and @angular/platform-browser@21.1.1 all declare peerDependencies: { "@angular/core": "21.1.1" } which is violated by 21.2.4. This cross-version mismatch can cause build failures, runtime errors from internal API changes between minor versions, or subtle behavioral bugs. All @angular/* packages should be at the same version.

(Refers to line 32)

Prompt for agents

The root cause is that @angular/core was bumped to 21.2.4 (likely via Dependabot) without updating the rest of the Angular packages. All @angular/* packages must be at the same version. To fix this, either:

1. Upgrade ALL Angular packages to 21.2.4: In package.json, change @angular/animations, @angular/common, @angular/compiler, @angular/forms, @angular/platform-browser, @angular/platform-browser-dynamic, @angular/router (in dependencies) and @angular/build, @angular/cli, @angular/compiler-cli (in devDependencies) from 21.1.1 to 21.2.4, then run bun install.

2. Or revert @angular/core back to 21.1.1 to match the other packages.

Option 1 is preferred if the intent was to upgrade Angular. After changing, verify with bun install and bun run build.

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[devin-ai-integration]

The Angular version mismatch (@angular/core at 21.2.4 vs other packages at 21.1.1) is a pre-existing issue on main — this PR only adds zone.js as a devDependency. The version skew is not introduced by this PR.