nw-bdd-methodology

# BDD Methodology for Acceptance Test Design ## Core Philosophy Test units of behavior, not units of code. Acceptance tests validate business outcomes through public interfaces, decoupled from implementation. ## Outside-In Double-Loop TDD The acceptance-designer creates the outer loop of Outside-In TDD. Development starts from user perspective, drives inward. **Outer loop (acceptance/BDD)**: Hours to days | User perspective, business language | Defines "done" | Scenarios describe user goals and observable outcomes, not internals | Failing outer-loop test is the starting signal for implementation **Inner loop (unit/TDD)**: Minutes | Developer perspective, technical terms | Software-crafter owns this loop Workflow: 1. Write failing acceptance test from user perspective (outer loop -- outside) 2. Software-crafter drops to inner loop: unit tests to implement components (inside) 3. Iterate inner loop until acceptance test passes 4. Passing acceptance test proves user value delivered 5. Repeat for next behavior Outer loop defines WHAT users need (outside). Inner loop drives HOW to build it (inside). ## Given-When-Then Structure ```gherkin Scenario: [Business-focused title describing one behavior] Given [preconditions - system state in business terms] When [single user action or business event] Then [observable business outcome] ``` ### Scenario Writing Rules **Rule 1: One scenario, one behavior** -- Split multi-behavior scenarios. **Rule 2: Declarative, not imper...