pixel-process-ug Acceptance Testing
Overview
Acceptance-driven backpressure connects specification acceptance criteria directly to test requirements, creating a validation chain that prevents premature completion claims. The system cannot cheat — you cannot claim a feature is done unless tests derived from spec acceptance criteria actually pass.
Announce at start: "I'm using the acceptance-testing skill to validate against specification criteria."
The Backpressure Chain
+------------+ derives +------------+ validates +------------+
| SPECS |---------------->| TESTS |---------------->| CODE |
| | | | | |
| Acceptance | | Test cases | | Must pass |
| Criteria | | from AC | | all tests |
+------------+ +------------+ +------------+
^ |
| backpressure |
+--------------------------------------------------------------+
If tests fail, implementation must change (not the spec or test)
Phase 1: Extract Acceptance Criteria
Goal: From each specification file, extract all Given/When/Then acceptance criteria.
Actions
- Locate all specification files (
specs/*.md) - Extract every acceptance criterion with its ID
- Document in structured format
Example Extraction
## From spec: 01-color-extraction.md
### AC-1: Extract dominant colors
- Given an uploaded image (PNG, JPG, or WebP)
- When color extraction is triggered
- Then 5-10 dominant colors are returned
- And each color includes hex, RGB, and HSL representations
### AC-2: Handle invalid images
- Given a corrupted or unsupported file
- When color extraction is attempted
- Then an appropriate error is returned
- And no partial results are produced
STOP — HARD-GATE: Do NOT proceed to Phase 2 until:
- All spec files are located and read
- Every acceptance criterion is extracted with an ID
- Criteria are in Given/When/Then format
- No criteria are ambiguous (if ambiguous, clarify with spec author)
Phase 2: Derive Test Cases
Goal: Map every acceptance criterion to at least one test case.
┌─────────────────────────────────────────────────────────────────┐
│ HARD-GATE: Every acceptance criterion must have at least one │
│ corresponding test. No exceptions. If a criterion has no │
│ test, the feature is NOT complete. │
└─────────────────────────────────────────────────────────────────┘
Traceability Table
| Acceptance Criterion | Test Type | Test Description | Test File:Line |
|---|---|---|---|
| AC-1: Extract dominant colors | Integration | Upload valid image, verify 5-10 colors with hex/RGB/HSL | test/color.test.js:15 |
| AC-2: Handle invalid images | Integration | Upload corrupted file, verify error, verify no partial data | test/color.test.js:42 |
Decision Table: Test Type for Acceptance Criteria
| Criterion Type | Test Type | Rationale |
|---|---|---|
| Data input/output behavior | Integration | Tests real data flow |
| Error handling behavior | Integration | Tests error paths end-to-end |
| Performance requirement | Load test | Requires measurement under load |
| UI behavior | E2E (Playwright) | Tests real browser interaction |
| Subjective quality | LLM-as-judge | Cannot be deterministically tested |
| Security requirement | Integration + security test | Tests authorization and input validation |
STOP — HARD-GATE: Do NOT proceed to Phase 3 until:
- Every acceptance criterion has at least one test mapped
- Test types are appropriate for the criterion type
- Test file locations are identified
Phase 3: Write Tests Before Implementation
Goal: Write acceptance tests that will fail until the feature is correctly implemented.
Actions
This phase integrates with test-driven-development:
- Write test from acceptance criterion (RED)
- Implement feature to pass test (GREEN)
- Refactor while keeping test green (REFACTOR)
Behavioral Outcome Focus
| Verify This (Behavioral) | NOT This (Implementation) |
|---|---|
| "5-10 colors are returned" | "K-means runs with k=8" |
| "Response time < 200ms" | "Cache is hit on second call" |
| "Error message is user-friendly" | "CustomError class is thrown" |
| "Data persists across sessions" | "PostgreSQL INSERT executes" |
| "UI updates within 500ms" | "WebSocket message is received" |
STOP — HARD-GATE: Do NOT proceed to Phase 4 until:
- All acceptance tests are written
- Tests fail before implementation (RED confirmed)
- Tests verify behavioral outcomes, not implementation details
Phase 4: Validation Gates
Goal: Before claiming any task complete, ALL gates must pass.
| Gate | Check | Tool | Required |
|---|---|---|---|
| Unit tests | All pass | Test runner | Always |
| Integration tests | All pass | Test runner | Always |
| Acceptance tests | All AC-derived tests pass | Test runner | Always |
| Build | Compiles without errors | Build tool | Always |
| Lint | No violations | Linter | Always |
| Typecheck | No type errors | Type checker | When applicable |
┌─────────────────────────────────────────────────────────────────┐
│ HARD-GATE: ACCEPTANCE │
│ │
│ Cannot claim completion without ALL acceptance tests passing. │
│ If any acceptance test fails, the feature is NOT done. │
│ Fix the implementation, not the spec or the test. │
└─────────────────────────────────────────────────────────────────┘
STOP — HARD-GATE: Do NOT proceed to Phase 5 until:
- All validation gates pass
- Acceptance tests pass with green status
- No gates are skipped or marked as "will fix later"
Phase 5: Traceability Report
Goal: Produce a report linking every spec criterion to its test and result.
Report Template
## Acceptance Test Report
| Spec | Criterion | Test | Status |
|------|-----------|------|--------|
| 01-color-extraction.md | AC-1: Extract dominant colors | test/color.test.js:15 | PASS |
| 01-color-extraction.md | AC-2: Handle invalid images | test/color.test.js:42 | PASS |
| 02-palette-rendering.md | AC-1: Render palette grid | test/palette.test.js:8 | PASS |
### Summary
- Total criteria: N
- Tested: N
- Passing: N
- Failing: 0
- Coverage: 100%
Anti-Patterns / Common Mistakes
| Anti-Pattern | Why It Is Wrong | Correct Approach |
|---|---|---|
| Changing specs to match implementation | Defeats the purpose of specification | Fix the implementation, not the spec |
| Skipping edge case criteria | Edge cases cause production bugs | ALL acceptance criteria get tests |
| Testing implementation details | Brittle tests that break on refactor | Test observable behavioral outcomes |
| Claiming "tests pass" without acceptance tests | Unit tests alone are insufficient | Acceptance tests are a separate, required category |
| Writing acceptance tests after implementation | Tests shaped to pass, not to specify | Write BEFORE implementation (TDD) |
| Deferring acceptance tests to "later" | Later never comes | Write them in Phase 2, before coding |
| Marking failing tests as "known issues" | Hides incomplete implementation | Fix the code until tests pass |
Rationalization Prevention
| Excuse | Reality |
|---|---|
| "The unit tests cover this" | Unit tests test components in isolation; acceptance tests verify integrated behavior |
| "The spec is obvious, no need for formal tests" | Obvious specs still need verifiable tests |
| "We can manually verify this" | Manual verification is not repeatable or trustworthy |
| "The acceptance criteria are too vague to test" | Clarify the criteria; vague specs produce vague code |
| "This is just a cosmetic change" | Cosmetic changes can break layout, accessibility, and UX |
Integration Points
| Skill | Relationship |
|---|---|
spec-writing |
Acceptance criteria come from specs |
test-driven-development |
TDD cycle uses acceptance-derived tests |
llm-as-judge |
For subjective criteria that cannot be deterministically tested |
verification-before-completion |
Final verification includes acceptance test check |
autonomous-loop |
Exit gate requires acceptance tests passing |
code-review |
Review checks acceptance test coverage |
planning |
Plan includes acceptance test writing as explicit tasks |
Skill Type
RIGID — The backpressure chain must not be bypassed. Every acceptance criterion must have a test. No completion without passing acceptance tests. Fix the implementation, not the spec or the test.