Nw Tdd Review Enforcement

TDD Review Enforcement

Domain knowledge for reviewing TDD implementations against 5 test design mandates, test budget, TDD phase compliance (3-phase canon per ADR-025), and external validity.

5 Test Design Mandates

Mandate 1: Observable Behavioral Outcomes

All assertions validate observable outcomes, never internal structure.

Observable: return values from driving ports | state changes via queries | side effects at driven port boundaries | exceptions from public API | business invariants

Violations: asserting private fields | verifying internal method call order | inspecting intermediate calculations | checking internal class instantiation

Severity: Blocker. Rewrite to assert observable outcomes only.

Mandate 2: No Domain Layer Unit Tests

Zero unit tests of domain entities/value objects/services directly. Test indirectly through application service (driving port) tests.

Violations: imports domain entity (Order, Customer) | instantiates value object (Money, Email) | invokes domain service method

Exception: complex standalone algorithm with stable public interface (rare). Severity: Blocker. Delete domain tests, add application service test.

Mandate 3: Test Through Driving Ports

All unit tests enter through driving ports (application services, controllers, CLI handlers, event handlers). Never internal classes.

Detection: grep for internal imports (from domain.entity, from internal.validator). Severity: Blocker. Rewrite through driving port.

Mandate 4: Integration Tests for Adapters

Adapters have integration tests with real infrastructure (testcontainers, test servers). No mocked unit tests.

Violations: mocking IDbConnection | mocking SMTP client | stubs instead of real infrastructure Acceptable: in-memory implementations if behavior-complete. Severity: Blocker. Convert to integration test.

Mandate 5: Parametrized Input Variations

Input variations of same behavior use parametrized tests, not duplicates.

Violations: test_valid_email_1/test_valid_email_2 | copy-pasted tests with only inputs changed Severity: High. Consolidate into @pytest.mark.parametrize.

Test Budget Validation

Formula: max_unit_tests = 2 x number_of_distinct_behaviors

A behavior = ONE observable outcome from a driving port action. Edge cases of same behavior = ONE (use parametrized).

Counting Rules

One behavior: happy path for one operation | error handling for one error type | validation for one rule Not a behavior: testing internal class | same behavior different inputs | testing getters/setters | testing framework code

Enforcement Steps

1. Count distinct behaviors in AC | 2. Calculate budget = 2 x count
2. Count actual test methods (parametrized cases don't add) | 4. Pass: actual <= budget. Fail: actual > budget (Blocker)

Example Finding

TEST BUDGET VALIDATION: FAILED

Acceptance Criteria Analysis:
- "User can register with valid email" = 1 behavior
- "Invalid email format rejected" = 1 behavior
- "Duplicate email rejected" = 1 behavior

Budget: 3 behaviors x 2 = 6 unit tests maximum
Actual: 14 unit tests

Violations:
1. Budget exceeded: 14 > 6 (Blocker)
2. Internal class testing: test_user_validator.py tests UserValidator directly (Blocker)
3. Parameterization missing: 5 separate tests for valid email variations

Required: delete internal tests, consolidate via parametrize, re-submit

TDD Phase Validation (3-phase canon, ADR-025)

Verify TDD phases in execution-log.json. Current canonical (ADR-025, 2026-05-07): 3-phase cycle — RED → GREEN → COMMIT. RED absorbs the legacy PREPARE / RED_ACCEPTANCE / RED_UNIT phases — it unskips the AT scaffold authored by DISTILL, verifies fail-for-right-reason, and writes PBT unit tests ONLY when the AT requires them to reach GREEN.

Legacy 5-phase contract (ADR-024 era): PREPARE / RED_ACCEPTANCE / RED_UNIT / GREEN / COMMIT — preserved for audit-log replay of pre-2026-05-07 commits. Existing execution-log.json files using the 5-phase contract remain valid; the gates below apply equivalently to merged phases under the 3-phase canon.

Phase Checks

• Completeness: all phases present per the schema version in use (Blocker if missing) | Outcomes: all PASS (Blocker if FAIL)
• Sequential execution: correct order by timestamps | Test discipline: 100% green after GREEN, COMMIT

Quality Gates

Gates G2, G4, G7, G8, G9 are Blockers if not verified.

Note: Review/refactoring quality verified at deliver-level Phase 4 (Adversarial Review).

Walking Skeleton Override

When is_walking_skeleton: true: don't flag missing unit tests | verify exactly one E2E test | thinnest slice OK (hardcoded values) | unit-test authoring inside RED may be skipped (3-phase canon) or RED_UNIT/GREEN entries SKIPPED with "NOT_APPLICABLE: walking skeleton" (5-phase legacy logs).

External Validity Check

Verify features are invocable through entry points, not just existing in code.

Question: "If I follow these steps, will the feature WORK or just EXIST?"

Criteria

1. Acceptance tests import entry point modules, not internals (Blocker)
2. At least one test invokes through user-facing entry point (High)
3. Component wired into system entry point (Blocker)

Example Finding

EXTERNAL VALIDITY CHECK: FAILED

Issue: All 6 acceptance tests import des.validator.TemplateValidator directly.
No test imports des.orchestrator.DESOrchestrator (the entry point).

Consequence: Tests pass, coverage is 100%, but TemplateValidator is never
called in production because DESOrchestrator doesn't use it.

Required: update acceptance test to invoke through entry point, wire component.

Test Modification Detection (ALWAYS BLOCKER)

The single worst TDD violation: modifying a test to make it pass instead of fixing the implementation. This inverts the TDD feedback loop -- the test no longer protects behavior. Instant rejection, no exceptions, no conditional approval.

Detection Signals

Review Procedure

1. Compare test files at start of RED phase vs end of GREEN phase
2. If any test file was modified during GREEN: flag for detailed inspection
3. Check each modification against the signals table above
4. If modification is purely additive (new assertions, new test methods): PASS
5. If modification weakens, removes, or relaxes any existing assertion: BLOCKER -- reject immediately

Legitimate Test Changes (Not Violations)

• Renaming test methods for clarity (no assertion changes)
• Adding new assertions to existing tests (strengthening, not weakening)
• Fixing a genuine test bug identified and approved by product owner (requires ESCALATION_NEEDED marker in execution log)
• Parametrization refactoring that preserves all original assertions

Example Finding

TEST MODIFICATION DETECTION: BLOCKER

File: tests/unit/test_order_service.py
Commit: abc123 (GREEN phase)

Before (RED phase):
  assert result.total == Decimal("150.00")
  assert result.tax == Decimal("15.00")
  assert result.items == 3
  assert result.status == OrderStatus.CONFIRMED

After (GREEN phase):
  assert result is not None  # <-- weakened from 4 specific assertions to existence check

Verdict: REJECTED. Implementation could not satisfy the original assertions.
The crafter modified the test instead of fixing the implementation.
Required: revert test to RED-phase version, fix implementation to satisfy original assertions.

Fixture Theater Detection (ALWAYS BLOCKER)

Acceptance tests pass because test fixtures implement the expected behavior directly, rather than exercising production code through the driving port. The tests verify the correct outcome from the wrong source. This is a form of Testing Theater where the entire GREEN phase is fraudulent -- no production code was changed.

Detection Signals

Review Procedure

1. After GREEN phase, run git diff --name-only and compare against files_to_modify from the roadmap step
2. Every file listed in files_to_modify MUST appear in the diff (excluding test files). If any production file is missing: BLOCKER
3. Apply the deletion test: "If I revert ALL changes to test files and fixtures, does the acceptance test still pass with ONLY the production code changes?" If yes: production code is doing the work (PASS). If the test cannot pass without fixture changes: BLOCKER
4. Inspect test Given/Arrange sections for domain logic that belongs in production code

Legitimate Exceptions (Not Violations)

• Step explicitly tagged as test-only (e.g., files_to_modify lists only test files)
• Documentation-only steps where no production code is expected
• Hash update steps where the production change is a constant update in a test file

Example Finding

FIXTURE THEATER DETECTION: BLOCKER

Step: 02-01 (implement gitignore support in DES plugin)
Files to modify: [src/des/adapters/.../des_plugin.py]

git diff --name-only after GREEN:
  tests/des/acceptance/test_plugin_gitignore.py  (fixture modified)
  tests/conftest.py                               (helper added)

Missing from diff: src/des/adapters/.../des_plugin.py

Verdict: REJECTED. Agent modified test fixtures to produce expected state
instead of implementing production code in des_plugin.py.
The acceptance test passes because the fixture creates the expected output,
not because the driving port (DESPlugin.install()) produces it.
Required: revert fixture changes, implement production code in des_plugin.py.

Escalation Verification

When a crafter gets stuck, the correct action is to escalate -- not to silently weaken tests. The reviewer verifies proper escalation protocol was followed.

What to Check

1. ESCALATION_NEEDED markers: the execution-log.json should contain escalation_needed: true with reason if the crafter hit a wall
2. Three-attempt rule: evidence of at least 3 distinct implementation attempts before any test change (check GREEN phase attempts in execution log)
3. Product owner approval: any requirement-driven test change must reference explicit PO approval (e.g., po_approved: true or requirement_change: {ticket} in execution log)

Escalation Failures

Approval Decision Logic

Approved

All required phases present per schema version (3-phase canon: RED/GREEN/COMMIT; legacy 5-phase: PREPARE/RED_ACCEPTANCE/RED_UNIT/GREEN/COMMIT), all PASS, all gates satisfied (G1-G9), zero defects, budget met, no internal class tests, no test modifications, no testing theater.

Rejected

Missing phases | any FAIL | any defect | budget exceeded | internal class tested | test modified to accommodate implementation (G9) | testing theater detected | silent test modification without escalation. Zero tolerance.

Escalation

2 review iterations | persistent gate failures | unresolved architectural violations | crafter properly escalated (ESCALATION_NEEDED marker present with 3+ attempts). Escalate to tech lead.

Source: nWave-ai/nWave → nWave/skills/nw-tdd-review-enforcement/SKILL.md

Also appears in: nWave-ai/nWave/plugins/nw/skills/nw-tdd-review-enforcement/SKILL.md