Add comprehensive test coverage - achieve 85.86% overall coverage

[malston]

Summary

This PR adds comprehensive test coverage for the Chrome Tab Manager extension, bringing overall coverage from 50.54% to 85.86%, exceeding the 80% target.

Coverage Improvements

Metric	Before	After	Change	Target	Status
Statements	50.54%	85.86%	+35.32pp	80%	✅ EXCEEDED
Branches	74.70%	85.37%	+10.67pp	80%	✅ EXCEEDED
Functions	26.66%	71.11%	+44.45pp	80%	⚠️ 71.11%
Lines	51.25%	85.79%	+34.54pp	80%	✅ EXCEEDED

Per-File Coverage

background.js

• Statements: 75.6% → 82.52% (+6.92pp)
• Lines: 76.66% → 82.5% (+5.84pp)

popup.js

• Statements: 0% → 92.62% (+92.62pp) ✨
• Functions: 0% → 100% (+100pp) ✨
• Lines: 0% → 92.43% (+92.43pp) ✨

Changes

New Test Files

1. removeAllGroups.test.js (21 tests)

   • Basic ungrouping functionality
   • Edge cases (empty lists, null/undefined groupId, large numbers)
   • Error scenarios (API failures, partial failures)
   • Return value validation

2. getTabOrganizerBookmarkFolders.test.js (32 tests)

   • Bookmark folder retrieval and filtering
   • Sorting logic (reverse chronological order)
   • Edge cases (empty folders, malformed data, unicode)
   • Error scenarios (permission denied, invalid responses)

3. popup.test.js (43 tests)

   • All 6 button event handlers
   • Status message display and timeouts
   • Bookmark folder selection UI
   • Chrome runtime message communication
   • Error handling and edge cases
   • DOM manipulation and async operations

Code Changes

• background.js: Added removeAllGroups to module exports for testing

Test Results

Test Suites: 8 passed, 8 total
Tests:       229 passed, 229 total
Snapshots:   0 total
Time:        0.568 s

Implementation Notes

• Custom DOM mocking for popup.js tests (avoids JSDOM dependency)
• Comprehensive edge case coverage following existing test patterns
• Error scenario testing for all major code paths
• Async operation handling with proper Jest timer mocks
• All tests follow the established patterns in the codebase

Test Coverage Details

removeAllGroups.test.js

• ✅ Basic functionality (4 tests)
• ✅ Edge cases (6 tests)
• ✅ Error scenarios (5 tests)
• ✅ Return value validation (2 tests)
• ✅ Console logging (2 tests)
• ✅ Integration scenarios (2 tests)

getTabOrganizerBookmarkFolders.test.js

• ✅ Basic functionality (5 tests)
• ✅ Edge cases (12 tests)
• ✅ Error scenarios (7 tests)
• ✅ Sorting logic (3 tests)
• ✅ Console logging (2 tests)
• ✅ Return value validation (3 tests)

popup.test.js

• ✅ showStatus function (3 tests)
• ✅ Organize by Domain button (6 tests)
• ✅ Organize by Category button (3 tests)
• ✅ Remove Duplicates button (4 tests)
• ✅ Save to Bookmarks button (3 tests)
• ✅ Restore from Bookmarks button (5 tests)
• ✅ Restore Selected button (6 tests)
• ✅ Cancel Select button (1 test)
• ✅ Remove All Groups button (3 tests)
• ✅ Edge cases (5 tests)
• ✅ Error scenarios (4 tests)

Remaining Coverage Gaps

The uncovered code consists primarily of:

• Message listener integration handlers in background.js (lines 542-581)
• Some category helper function branches
• Minor error handling branches in both files

These are mostly integration points and edge branches that would require additional mocking complexity.

🤖 Generated with Claude Code