Testing Domain

Overview

Validate domain rules and invariants without UI or infrastructure dependencies.

Focus areas

• Entity and value object behavior
• Aggregate invariants
• Domain services
• Application use cases (when pure)

Definition of done (DoD)

• New domain logic has corresponding unit tests
• Tests cover happy path + at least one edge/error case
• Tests are deterministic (no random, no DateTime.Now)
• Tests run in under 1 second each
• No infrastructure/UI dependencies in domain tests

Workflow

1. Build fixtures for domain objects.
2. Test invariants and edge cases.
3. Keep tests fast and deterministic.
4. Avoid infrastructure dependencies.

Guidance

• Use builders/factories to reduce test setup noise.
• Prefer explicit assertions over snapshots.
• Name tests after the rule being validated.

References

• references/fixtures.md for fixture patterns.
• references/invariant-tests.md for invariant coverage.