test-from-spec

name	test-from-spec
description	Generate unit tests from a spec's acceptance criteria. Use when: you have a written spec and need tests, generate tests from spec, TDD from spec, spec to tests.

Test from Spec

Generate unit tests that cover every acceptance criterion in a spec.

When to Use

• A spec is written and approved
• You're starting the TDD cycle (tests before code)
• You want to verify spec coverage with tests

Procedure

1. Read the spec file indicated by the user (or search specs/ directory)
2. Extract all acceptance criteria (the Given...When...Then items)
3. For each criterion, generate at least one test:
   • Happy path test for the main behavior
   • Edge case tests if the spec mentions edge cases
   • Error case tests for failure scenarios
4. Follow the existing test patterns in the project:
   • Same test framework
   • Same file naming convention
   • Same assertion library
   • Same fixture/helper patterns
5. If no existing tests are found, ask the user which framework to use
6. Save test files next to the source files they test (colocated)

Rules

• One test per behavior — each test verifies exactly one acceptance criterion
• Test names must be descriptive enough to serve as documentation
• Tests must be self-contained — no shared mutable state between tests
• Do NOT implement the production code — only write the tests
• Tests should fail initially (red phase of TDD)

Output

For each acceptance criterion, produce:

Criterion: "Given X, when Y, then Z"
Test: test_file.ext → test function name

Then write the actual test code.