Fix 22 failing tests: Compression platform guards, FHIR XML round-trip, ObjectPool regression

[Copilot]

Description

Resolve all 22 remaining test failures: 17 CompressionTests (platform), 4 FHIRXMLSerialization (broken round-trip), 1 ObjectPool regression (incorrect test math). Test suite now at 3073 passing, 0 failures.

Related Issues

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance improvement
• Documentation update
• Code refactoring
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Security fix

Changes Made

CompressionTests — 17 failures → 17 skips

• Added requireCompression() helper using #if !canImport(Compression) + XCTSkip. Apple's Compression framework doesn't exist on Linux; tests now skip cleanly instead of throwing unexpected errors.

FHIRXMLSerialization — 4 failures → 0

• XML encoder: primitive arrays (given: ["Alice"]) were silently dropped. Fixed buildElement to recurse on non-dict array items.
• XML decoder: added convertToFHIRJSON() post-processing in FHIRXMLParser:
  • Unwraps root element name → resourceType
  • Flattens {"value": "x"} → "x" for FHIR primitive types
  • Filters xmlns attributes
  • FHIR-aware array field mapping (fhirArrayFields) to correctly wrap single-element arrays
• Test XML: added required messageID/timestamp fields to manually-crafted XML in testResourceContainerXMLDecoding

ObjectPool regression — 1 failure → 0

• Original test: preallocate(20) then acquire(100) sequentially = 20/100 = 20% reuse, but asserted >30%. Mathematically impossible.
• Fix: two-cycle acquire-release pattern. First cycle populates pool, second cycle demonstrates reuse → 70%.

milestone.md — Updated test stats and fix details.

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Performance tests added/updated
• Code coverage ≥ 90%

Manual Testing

swift test  # 3073 passed, 17 skipped (compression/Linux), 0 failures
swift test --filter CompressionTests        # 8 passed, 17 skipped
swift test --filter FHIRXMLSerializationTests  # 13 passed
swift test --filter testObjectPoolRegressionBaseline  # 70% reuse, passed

Documentation

• API documentation added/updated (DocC comments)
• README.md updated (if applicable)
• Examples updated (if applicable)
• CHANGELOG.md updated under "Unreleased" section
• Migration guide updated (if breaking change)

Standards Compliance

• HL7 v2.x (version: _____)
• HL7 v3.x / CDA
• FHIR (version: R4) — XML serialization round-trip now works correctly

Checklist

• My code follows the project's style guidelines (CODING_STANDARDS.md)
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published
• I have checked my code for security vulnerabilities
• I have removed all PHI/sensitive data from tests and examples

Performance Impact

• Throughput: no change
• Latency: no change
• Memory usage: no change

Breaking Changes

None.

Screenshots (if applicable)

N/A

Additional Notes

The fhirArrayFields mapping in FHIRXMLParser covers Patient, Observation, Practitioner, MedicationRequest, Bundle, Encounter, and common complex types. New resource types will need entries added if they use single-element arrays in XML round-trips.

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For Reviewers:

• Code quality and style
• Test coverage adequate
• Documentation complete
• No security concerns
• Performance acceptable
• Standards compliance verified

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