Testing

• Must use TDD. Write tests first and follow red, green, refactor
• Must not use let or before in specs (avoid mystery guests). Do test setup within each test.
• Test behaviour, not implementation. Four Phase Test: setup, exercise, verify, teardown.
• Test pyramid: many model/PORO unit specs, some request specs, few system specs.
• Every public method on every model and PORO must have at least one spec.
• Every branch in a conditional must have at least one spec.
• Use build / build_stubbed over create unless persistence is needed.
• Factories: only required attributes with sensible defaults. Start in spec/factories.rb.
• Shoulda Matchers for validations and associations.
• WebMock blocks all external HTTP in tests — always stub external requests.
• One expect per it block. Max 2 levels of context nesting.
• Never test private methods directly. Never stub the system under test.