BDD Test Implementation Patterns

Philosophy: Specifications Drive Implementation

BDD test implementation is NOT "writing tests" - it is making specifications executable.

The specification (.feature file or hypothesis declaration) already exists. Your job is to:

1. Translate Given/When/Then into Effect.gen programs
2. Provide the Effect Layer dependencies for service isolation
3. Assert on outcomes, not function calls (verify gridData.length > 0, not "setGridData was called")
4. Maintain step definitions as living documentation (clear, readable, 1:1 with specs)

Canonical principle: If your step definition contains complex logic, the specification is wrong. Fix the spec first.

Canonical Sources