Port RE2 regex tests to improve test coverage #120845
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Co-authored-by: stephentoub <[email protected]>
Co-authored-by: stephentoub <[email protected]>
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[WIP] Port re2 regex tests to improve coverage
Port RE2 regex tests to improve test coverage
Oct 17, 2025
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October 17, 2025 14:10
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Pull Request Overview
Ports a subset of RE2's functional regex tests into the .NET test suite to expand coverage across multiple regex engines.
- Adds 142 test cases derived from RE2's re2_test.cc and search_test.cc.
- Updates test project file to include the new test file and adds RE2's BSD 3-Clause license to third-party notices.
- Exercises diverse regex features (anchors, word boundaries, quantifiers, escapes, Unicode) across all available engines.
Reviewed Changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| THIRD-PARTY-NOTICES.TXT | Adds RE2 BSD 3-Clause license attribution for the ported tests. |
| System.Text.RegularExpressions.Tests.csproj | Includes the new RegexRe2Tests.cs file in the test compilation. |
| RegexRe2Tests.cs | Introduces the ported RE2-derived test cases and supporting data generation logic. |
src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexRe2Tests.cs
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src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexRe2Tests.cs
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src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexRe2Tests.cs
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stephentoub
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Oct 17, 2025
src/libraries/System.Text.RegularExpressions/tests/FunctionalTests/RegexRe2Tests.cs
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Removed 57 test cases that were already covered by existing tests in PCRE, Rust, or core regex tests: - Basic patterns like "a", "a*", "a+", "a?" with simple inputs - Simple anchor tests "^$", "^", "$" that duplicate existing coverage - Trivial quantifier tests already well-tested elsewhere - Basic UTF-8 tests with single character patterns Retained 85 unique test cases that add value: - Complex patterns and edge cases - Word boundary tests with various scenarios - Multiline mode tests - Case-insensitive matching - Octal/hexadecimal escapes - Non-trivial quantifier combinations Co-authored-by: stephentoub <[email protected]>
Copilot finished work on behalf of
stephentoub
October 17, 2025 14:49
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Oct 17, 2025
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MihaZupan
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Oct 17, 2025
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This PR ports functional regex tests from the RE2 test suite to improve .NET's regex test coverage, as requested in #120756.
Changes
Test Suite Additions
RegexRe2Tests.cs: New test file containing 85 unique test cases ported from RE2'sre2_test.ccandsearch_test.ccTest Categories Covered
The ported tests validate:
^,$) in single-line and multiline modes with non-trivial cases\b,\B) with ASCII and special characters\141, hexadecimal\x61, unicode\u0061)(?i)){n},{n,},{n,m})Compatibility Adjustments
Several RE2-specific patterns were excluded or adapted for .NET compatibility:
\Cpatterns: RE2's byte-matching construct is not supported in .NET\Q...\Epatterns: Quote meta syntax is not supported in .NET\x{...}escapes: Changed to .NET-compatible\x(2 digits) or\u(4 digits) formatRegexHelpers.IsNonBacktracking()checkLicense Attribution
THIRD-PARTY-NOTICES.TXT: Added RE2 BSD 3-Clause license to properly attribute the ported tests.csproj: AddedRegexRe2Tests.csto the compilationTesting
All 29,621 tests pass successfully, including the newly ported RE2 tests across all regex engines.
Fixes #120756
Original prompt
Fixes #61896
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