Add code coverage

[colemancda]

Summary

Code coverage

• Add Scripts/coverage.sh, which runs the test suite with coverage instrumentation, exports LCOV (coverage.lcov) and Cobertura (coverage.xml) reports to .build/coverage/, and fails if line coverage of the package sources drops below a threshold.
• Add a coverage job to CI that enforces a 95% minimum (current: 96.98%, up from 66.57%), uploads the report to GitHub Code Quality for per-PR coverage display, and archives both reports as a build artifact.
• CI now triggers only on push (plus manual workflow_dispatch), eliminating duplicate push + pull_request runs.

Tests (104 total, 68 new)

• BindingFormatTests — UUID/Date/Data bindings, Julian day and ISO8601 conversion
• LocationAndAffinityTests — Connection.Location, URIQueryParameter, all five TypeAffinity rules
• ValueAccessTests — every Binding conversion and BindingConvertible conformance, Column.Value, Row reading of all five value types
• ConnectionStatementTests — connection properties, extended error codes, execute limits, bind/step error paths
• FunctionEdgeCaseTests — function/collation removal, all argument and result types, window-function xInverse/empty-frame paths, schema DEFAULT clauses, registration failures, stale-error column reads
• OfficialSuitePortTests — representative cases ported from SQLite's official TCL test suite (select1, null, types, expr, insert/delete/update, collate1), via a TCLHarness wrapper reproducing execsql/catchsql semantics

Verified on Linux via Docker (swift:6.3.3, matching the CI container) in addition to macOS.

Bug fixes found by the new tests

• Use-after-free in function registration: when SQLite rejects a registration (argument count above SQLITE_MAX_FUNCTION_ARG), it invokes the xDestroy destructor itself; the library also released the callback box manually, crashing with SIGSEGV. Fixed for scalar, aggregate, and window functions (collations correctly keep the manual release, since sqlite3_create_collation_v2 does not call xDestroy on failure).
• Case-sensitive BLOB affinity rule: TypeAffinity("blob") returned NUMERIC instead of BLOB because rule 3 checked the non-uppercased string.
• Discarded SQLite diagnostics: failed statement preparation threw a generic "Unable to initialize statement." instead of SQLite's own message (e.g. "no such table: t").
• Stale test expectation: the bundled data.sqlite contains 6099 rows in site_amenities, not 5932.

Remaining uncovered lines (~3%) are defensive guards (nil sqlite3_context in C callbacks, allocation-failure paths, impossible switch defaults) that cannot be triggered without inducing crashes.

Test plan

• All 104 tests pass on macOS
• All tests pass on Linux (Docker, swift:6.3.3)
• Scripts/coverage.sh exits 0 at the 95% threshold and produces both report files
• CI green across macOS, Linux, Android, and Windows

[github-code-quality]

Code Coverage Overview

Languages: Swift

Swift / code-coverage/llvm-cov

The overall coverage in the feature/unit-tests branch is 97%. Coverage data for the master branch is not yet available.

Show a code coverage summary of the most covered files.

File	master	feature/unit-tests c4460fa	+/-
Sources/SQLite/Binding.swift	—	100%	—
Sources/SQLite/Schema.swift	—	100%	—
Sources/SQLite/...Statement.swift	—	100%	—
Sources/SQLite/Column.swift	—	100%	—
Sources/SQLite/...eAffinity.swift	—	100%	—
Sources/SQLite/Function.swift	—	98%	—
Sources/SQLite/Statement.swift	—	97%	—
Sources/SQLite/...onnection.swift	—	96%	—
Sources/SQLite/...eFunction.swift	—	87%	—
Sources/SQLite/...wFunction.swift	—	87%	—

---

_{Updated July 18, 2026 01:35 UTC
Code Coverage is in Public Preview. Learn more and provide us with your feedback.}