testing

name	testing
description	The how of testing: pyramid, AAA, isolation, risk coverage, determinism. Guarantees the DoD's "tests are green". test-expert-csk applies it. Trigger phrases: "write a test", "run the tests", "coverage", "are the tests green", "unit test", "integration test"

Testing Discipline

Goal: behavior correctness — test real behavior without breaking product code just to make a test pass.

Principles

• Pyramid: many unit, fewer integration, few end-to-end (e2e). Limit e2e to critical flows.
• AAA: Arrange-Act-Assert; one test = one behavior.
• Isolation & determinism: external dependencies are mocked/faked; time and randomness are fixed; test order is independent.
• Risk-coverage: risk, not metrics. Critical path + boundary + negative + authorization (IDOR/404) scenarios.
• Naming: what_it_tests_under_which_condition_what_it_expects — on failure it is clear what broke.
• Red-green: first a failing test, then the implementation.

Watch out

• Flaky = bug: an occasionally failing test is not tolerated; it is fixed at the root.
• In snapshot/golden-file tests, avoid needless brittleness (assert only the meaningful output).

DoD (this skill's contribution)

• The relevant test command is green (e.g. dotnet test); critical paths are covered; no empty/meaningless tests.