Add property-based tests for JSON serialization, records, and state

[tbhb]

Summary

• Add comprehensive property-based tests using Hypothesis for JSON serialization roundtrip, record validation, and state computation
• Create shared strategies.py module with reusable Hypothesis strategies for JSONLT domain types
• Rename test_key_comparison.py to test_key_properties.py for naming consistency across property test files

Test coverage

The new property-based tests verify:

JSON serialization (test_json_properties.py)

• Roundtrip preservation: parse(serialize(obj)) == obj
• Serialization determinism: consistent output for identical data
• Valid JSON output: parseable by standard json.loads

Record validation (test_record_properties.py)

• Valid scalar and compound key records pass validation
• Key extraction matches field values
• Tombstone detection and construction roundtrip

State computation (test_state_properties.py)

• Empty sequence yields empty state
• Upsert idempotence and last-write-wins semantics
• Delete operations and reinsert-after-delete
• State invariants: no tombstones in final state, keys match extracted keys

Test plan

• All 28 property tests pass locally
• Type checking passes with 0 errors
• All linting checks pass
• CI passes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[codspeed-hq]

CodSpeed Performance Report

Merging #11 will not alter performance

_{Comparing property-tests (68d373b) with main (6ed513b)¹}

Summary

✅ 173 untouched
⏩ 1 skipped²

Footnotes

1. No successful run was found on main (7373632) during the generation of this report, so 6ed513b was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 1 benchmark was skipped, so the baseline result was used instead. If it was deleted from the codebase, click here and archive it to remove it from the performance reports. ↩