Umbraco-CMS/docs/plans/phase-1-baseline-testing-summary.md

# Phase 1: Baseline Testing - Completion Summary

**Date:** 2025-12-07
**Plan Reference:** [2025-12-07-string-extensions-refactor-plan.md](./2025-12-07-string-extensions-refactor-plan.md)

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## Overview

Phase 1 established comprehensive test coverage and performance baselines for the `StringExtensions` methods targeted for optimization. This phase ensures we can safely refactor while measuring improvement.

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## Task 1: Existing Unit Tests

**File:** `tests/Umbraco.Tests.UnitTests/Umbraco.Core/Extensions/StringExtensionsTests.cs`

### Test Results
- **Tests Run:** 119
- **Passed:** 119
- **Failed:** 0
- **Skipped:** 1 (Windows-only platform test)

### Coverage Status
All targeted methods have comprehensive existing test coverage:
- `StripWhitespace()` - ✅ Covered
- `GetFileExtension()` - ✅ Covered
- `StripHtml()` - ✅ Covered
- `IsLowerCase()` - ✅ Covered
- `IsUpperCase()` - ✅ Covered
- `ReplaceNonAlphanumericChars()` - ✅ Covered

### Conclusion
Strong existing test suite provides safety net for refactoring. All tests passing confirms current implementation correctness.

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## Task 2: New Performance Tests

**File:** `tests/Umbraco.Tests.UnitTests/Umbraco.Core/Extensions/StringExtensionsPerformanceTests.cs`

### Test Coverage
- **Test Methods:** 6
- **Test Cases:** 25 total
- **Status:** All tests pass

### Tests Added

1. **`StripWhitespace_Performance_Tests`** (5 cases)
   - Empty string
   - String without whitespace
   - String with mixed whitespace (spaces, tabs, newlines)
   - String with only whitespace
   - Large string with scattered whitespace

2. **`GetFileExtension_Performance_Tests`** (4 cases)
   - Simple extension
   - Multiple dots
   - No extension
   - Edge cases

3. **`StripHtml_Performance_Tests`** (4 cases)
   - Simple HTML
   - Nested tags
   - Mixed content
   - Self-closing tags

4. **`IsLowerCase_Performance_Tests`** (4 cases)
   - All lowercase
   - All uppercase
   - Mixed case
   - Numbers and special characters

5. **`IsUpperCase_Performance_Tests`** (4 cases)
   - All uppercase
   - All lowercase
   - Mixed case
   - Numbers and special characters

6. **`ReplaceNonAlphanumericChars_Performance_Tests`** (4 cases)
   - Special characters only
   - Alphanumeric only
   - Mixed content
   - Empty string

### Important Notes

**Test Expectations Corrected:**
- Initial plan expectations for `IsLowerCase`/`IsUpperCase` digit handling were updated to match actual implementation behavior (digits return `false` for both methods)
- `ReplaceNonAlphanumericChars` test expectations were corrected to match current implementation (replacement character applied per spec)

### Commit
- **Hash:** `609c7f89`
- **Message:** "test: add baseline tests for StringExtensions performance methods"

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## Task 3: Benchmark Baseline

**File:** `tests/Umbraco.Tests.Benchmarks/StringExtensionsBenchmarks.cs`

### Benchmark Results

| Method | Mean | Allocated |
|--------|------|-----------|
| `StripWhitespace_Benchmark` | 660.54 ns | 64 B |
| `GetFileExtension_Benchmark` | 463.78 ns | 552 B |
| `StripHtml_Benchmark` | 733.88 ns | 48 B |
| `IsLowerCase_Benchmark` | 24.97 ns | 48 B |
| `IsUpperCase_Benchmark` | 25.24 ns | 48 B |
| `ReplaceNonAlphanumericChars_String_Benchmark` | 610.93 ns | 1304 B |

### Observations

**High-Priority Optimization Targets:**
1. **`ReplaceNonAlphanumericChars`** - Highest allocation (1304 B), moderate execution time
2. **`StripWhitespace`** - Moderate performance, low allocation
3. **`StripHtml`** - Slowest execution (733.88 ns), low allocation

**Lower-Priority Targets:**
4. **`GetFileExtension`** - Moderate performance, high allocation (552 B) relative to task
5. **`IsLowerCase`** / **`IsUpperCase`** - Already fast (<25 ns), minimal allocation

### Test Input Data
- `StripWhitespace`: "This    is   a   test   string   with   lots   of   spaces"
- `GetFileExtension`: "/path/to/some/file.with.multiple.dots.txt"
- `StripHtml`: "<p>This is <strong>HTML</strong> content with <a href='#'>links</a></p>"
- `IsLowerCase` / `IsUpperCase`: "ThiS iS a TeSt StRiNg WiTh MiXeD cAsE"
- `ReplaceNonAlphanumericChars`: "Hello@World#2024!Test$String%With&Special*Chars"

### Commit
- **Hash:** `3d6ebe55`
- **Message:** "perf: add benchmarks for StringExtensions methods to optimize"

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## Phase 1 Success Metrics

✅ **All Success Criteria Met:**
- [x] Existing tests identified and passing (119/119)
- [x] New performance tests added and passing (25 test cases)
- [x] Benchmark baseline established for all 6 target methods
- [x] No regressions introduced
- [x] Documentation complete

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## Next Steps (Phase 2)

With baseline established, Phase 2 will implement optimizations:

1. **Span-based refactoring** for methods with high allocation
2. **Regex compilation** for pattern-matching methods
3. **Algorithm improvements** based on benchmark insights

**Expected Improvements:**
- 30-50% reduction in execution time
- 40-60% reduction in memory allocation
- Maintained or improved test coverage

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## Files Modified

### Created
- `tests/Umbraco.Tests.UnitTests/Umbraco.Core/Extensions/StringExtensionsPerformanceTests.cs`
- `tests/Umbraco.Tests.Benchmarks/StringExtensionsBenchmarks.cs`
- `docs/plans/phase-1-baseline-testing-summary.md` (this file)

### No Changes Required
- `tests/Umbraco.Tests.UnitTests/Umbraco.Core/Extensions/StringExtensionsTests.cs` (existing tests already comprehensive)

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## Conclusion

Phase 1 successfully established a robust foundation for the StringExtensions refactoring effort. With 119 existing tests passing, 25 new performance test cases, and detailed benchmark baselines, we can confidently proceed with optimization work while ensuring zero regressions.

The benchmark data clearly identifies `ReplaceNonAlphanumericChars`, `StripWhitespace`, and `StripHtml` as the highest-value optimization targets, guiding Phase 2 priorities.