evilissimo/software-design
Use before implementing or refactoring software. Contains two skills: (1) Modular Software Design — for designing module boundaries, APIs, layers, abstractions, services, repositories, adapters, or architecture, helping reduce total system complexity by creating deep modules, hiding implementation knowledge, avoiding leakage and pass-through APIs, comparing alternative designs, documenting interfaces before coding, and critiquing existing architecture; and (2) Software Testing — for writing unit tests, integration tests, or end-to-end tests, creating mocks/stubs/fakes, designing a testing strategy, doing TDD, reviewing test quality, fixing flaky tests, or refactoring test suites, generating risk-focused test plans, picking appropriate test levels, choosing between mocks/fakes/real dependencies, and applying Arrange-Act-Assert patterns with concrete examples.
93
94%
Does it follow best practices?
Impact
92%
1.12xAverage score across 5 eval scenarios
Passed
No known issues
test-smells.mdskills/software-testing/references/
Test Smells
Overspecified Tests
Tests assert private methods, exact call order, or internal choreography. Fix by asserting observable behavior through public seams.
Over-Mocking
Many internal collaborators or third-party types are mocked. Fix by testing cohesive behavior together, using fakes for owned boundaries, and wrapping third-party libraries behind adapters.
Weak Assertions Under High Coverage
Tests execute code but only assert non-null results, snapshots, or absence of exceptions. Fix by checking business-relevant outputs, persisted effects, emitted events, or boundary interactions.
Flaky or Slow Tests
Failures depend on time, ordering, network, shared state, random data, or external services. Fix by isolating state, controlling clocks/randomness, replacing unsafe dependencies, and moving only necessary checks to slower levels.
Mystery Guests
Tests rely on hidden files, fixtures, or global setup. Fix by making data local, named, and purpose-built.
Duplicated or Over-Abstracted Test Logic
Helpers obscure the scenario or assert too much. Fix by keeping tests short, explicit, and domain-named.
Untestable Design
Outcomes are hidden behind implicit dependencies or oversized classes. Fix by exposing stable outputs, domain objects, events, or adapters.