test: isolate malformed flags during UFC ingestion - #26
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# Conflicts: # README.md # ufc-config.json
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## Motivation Malformed per-flag UFC configuration is already isolated during ingestion: libdatadog stores a rejection error for that key while compiling valid neighboring flags normally. The FFI translation incorrectly exposed that rejection as a normal DEFAULT result with no error code, hiding a configuration bug from callers. This implements the contract merged in [DataDog/ffe-system-test-data#26](DataDog/ffe-system-test-data#26): evaluating a rejected key returns the caller default with ERROR / PARSE_ERROR, while valid neighboring flags remain usable. ## Changes - Map FlagConfigurationInvalid to the FFI ERROR reason and PARSE_ERROR error code. - Add regression coverage proving an invalid regex flag does not poison a valid neighboring flag. - Bump the canonical fixture submodule to the revision merged in [DataDog/ffe-system-test-data#26](DataDog/ffe-system-test-data#26). - Update the canonical adapter to expect PARSE_ERROR for rejected keys. - Compare semantic versions by precedence so build metadata does not change equality or ordering. - Correct the regex-ingestion documentation to match the parser behavior. ## Decisions - Keep validation in libdatadog so the same Rust regex and UFC parsers used for evaluation own rejection decisions. - Retain only the per-key rejection error in the compiled configuration, not the malformed flag object. - Preserve FLAG_NOT_FOUND for keys absent from the configuration. - Use SemVer precedence comparisons, which ignore build metadata as required by the specification. ## Validation - [x] cargo test -p libdd-ffe - [x] cargo test -p libdd-ffe-ffi rejected_flag_is_exposed_as_parse_error - [x] cargo test -p libdd-ffe-test-suite --test canonical_fixtures - [x] git diff --check Co-authored-by: leo.romanovsky <leo.romanovsky@datadoghq.com>
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Motivation
This PR adds regression coverage for bugs in malformed-flag handling. A single invalid flag can currently poison an otherwise usable UFC, fall through to a catch-all allocation, or be misreported as a normal default or missing flag. These behaviors hide configuration errors and unnecessarily break valid neighboring flags.
The corrected contract isolates each malformed flag during ingestion, keeps the rest of the UFC usable, and reports the rejected key accurately as ERROR / PARSE_ERROR.
Changes
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Validation