write-tests

name	write-tests
description	Add Swift Testing coverage in Tests/Domain, Tests/Invariants, Tests/Integration, or package-local suites. Use when adding behaviour, reproducing a bug, or the user asks for more tests.

Write tests

Swift Testing only (@Test, #expect, @Suite). No new XCTest modules.

Where it goes

Kind	Path
Example-based public API	Tests/Domain/
Seeded invariant ("for any input")	Tests/Invariants/
Golden fixtures, live capture, pipelines	Tests/Integration/
Package-private details	Packages/<Name>/Tests/

DiffuseTestSupport (Tests/Support) has SnapshotBuilder, TestSchema, FakeCapabilityFactory, SeededGenerator, SnapshotSummary.stub, TemporaryLibrary.

Rules

• Prefer fakes over live hardware. Integration live-capture tests are the exception.
• Deterministic clocks (FixedTimeSource) and ids. No Date() or UUID() in assertions unless the test is specifically about allocation.
• If you change collector schema, run skill fixtures and explain the diff.
• After writing tests: swift test --parallel then ./Scripts/coverage.sh.

Shape

One behaviour per @Test with a sentence name ("Pinned snapshots survive the age window"). Invariants take arguments: of seeds and mention the seed in the failure message.