acceptance-test-from-criteria

acceptance-test-from-criteria

Overview

Per ISTQB Glossary V4.7.1: ATDD (Acceptance Test-Driven Development) is "a collaboration-based test-first approach that defines acceptance tests in the stakeholders' domain language."

The shift-left flow:

Story → AC → Acceptance test (this skill) → Implementation → Pass

The acceptance test is written first (test-first); the implementation follows; success = test passes.

This is BDD's variant where the AC is the source of truth; the test is the executable formalization.

When to use

• The team practices ATDD (test-first from acceptance criteria).
• Each story's acceptance is gated on the corresponding tests passing.
• The team wants AC-to-test traceability for compliance / audit.

For Gherkin generation from prose stories, see gherkin-from-stories. For upstream AC extraction, see acceptance-criteria-extractor.

Step 1 - Read the AC list

## Acceptance criteria

- AC-1.1: Valid promo "WELCOME10" reduces subtotal by 10%.
- AC-1.2: Expired promo shows the message "This code has expired."
- AC-1.3: Empty promo input shows "Please enter a code."
- AC-1.4: Already-applied promo shows "Already applied" without re-applying.
- AC-1.5: Promo applies before tax (per current pricing logic).

Each AC has an ID - preserved end-to-end so test failures map back.

Step 2 - One test per AC

# Features/promo-application.feature
Feature: Apply promo code at checkout

  Background:
    Given a logged-in customer
    And the cart contains 1 of "BOOK-001" at $24.99

  @AC-1.1
  Scenario: Valid promo reduces subtotal
    Given promo code "WELCOME10" is active
    When I enter "WELCOME10" in the promo input
    And I click "Apply"
    Then the subtotal updates to $22.49

  @AC-1.2
  Scenario: Expired promo shows error
    Given promo code "EXPIRED50" is inactive
    When I enter "EXPIRED50" in the promo input
    And I click "Apply"
    Then an error appears: "This code has expired"

  @AC-1.3
  Scenario: Empty promo input
    When I enter "" in the promo input
    And I click "Apply"
    Then an error appears: "Please enter a code"

  @AC-1.4
  Scenario: Already-applied promo
    Given promo code "WELCOME10" is active
    And I have already applied "WELCOME10"
    When I enter "WELCOME10" in the promo input
    And I click "Apply"
    Then an error appears: "Already applied"
    And the subtotal remains $22.49

  @AC-1.5
  Scenario: Promo applies before tax
    Given the tax rate for this region is 10%
    And promo code "WELCOME10" is active
    When I enter "WELCOME10" in the promo input
    And I click "Apply"
    Then the subtotal updates to $22.49
    And the tax updates to $2.249 (10% of $22.49)
    And the total is $24.74

The @AC-X.Y tag is the load-bearing traceability: failing tests report which AC failed.

Step 3 - Initial state - all tests fail

Per ATDD, tests are written before implementation. Initial run:

Scenario: Valid promo reduces subtotal
  Given promo code "WELCOME10" is active                    # PASS (admin seeding works)
  When I enter "WELCOME10" in the promo input               # PASS (input field exists)
  And I click "Apply"                                        # PASS (button exists)
  Then the subtotal updates to $22.49                       # FAIL — promo logic not implemented

5 of 5 scenarios FAILED (as expected — implementation pending).

The failing tests are the work backlog.

Step 4 - Implementation drives tests green

Engineer implements the promo logic; tests turn green one by one:

After implementing valid-promo path:
  AC-1.1 ✅
  AC-1.2 ❌ (expired logic still missing)
  AC-1.3 ❌
  AC-1.4 ❌
  AC-1.5 ❌

After implementing all paths:
  AC-1.1 ✅
  AC-1.2 ✅
  AC-1.3 ✅
  AC-1.4 ✅
  AC-1.5 ✅

Story is "done" only when all AC tests pass - per the team's DoD (definition-of-done).

Step 5 - Scaffold new step definitions

The skill detects undefined steps and emits stub definitions:

# features/steps/promo_steps.py

@given('promo code "{code}" is active')
def step_promo_active(context, code):
    raise NotImplementedError(f"Implement: seed promo {code} as active")

@given('promo code "{code}" is inactive')
def step_promo_inactive(context, code):
    raise NotImplementedError(f"Implement: seed promo {code} as expired")

@when('I enter "{code}" in the promo input')
def step_enter_promo(context, code):
    raise NotImplementedError(f"Implement: type {code} in promo input")

@when('I click "{label}"')
def step_click(context, label):
    raise NotImplementedError(f"Implement: click {label}")

@then('an error appears: "{message}"')
def step_error_appears(context, message):
    raise NotImplementedError(f"Implement: assert error message {message}")

@then('the subtotal updates to ${expected:f}')
def step_subtotal(context, expected):
    raise NotImplementedError(f"Implement: assert subtotal == {expected}")

The NotImplementedError body makes the test failure helpful - the engineer knows exactly what to implement.

The implementations land in PRs alongside the production code.

Step 6 - Traceability artifact

## AC-to-test mapping — `<story>` (auto-generated)

| AC ID    | Test                                               | Status   | Last run |
|----------|----------------------------------------------------|----------|----------|
| AC-1.1    | `promo-application.feature:8` (Valid promo)         | ✅ pass  | 2026-05-05 |
| AC-1.2    | `promo-application.feature:14` (Expired)            | ✅ pass  | 2026-05-05 |
| AC-1.3    | `promo-application.feature:20` (Empty)              | ✅ pass  | 2026-05-05 |
| AC-1.4    | `promo-application.feature:25` (Already applied)    | ✅ pass  | 2026-05-05 |
| AC-1.5    | `promo-application.feature:32` (Tax interaction)    | ✅ pass  | 2026-05-05 |

**Coverage:** 5/5 AC covered by tests. Story is testable per ATDD.

This artifact answers: "Did we test what the customer asked for?" A 1:1 mapping of AC → test → status answers it definitively.

Step 7 - Run via the team's framework

Default: match the team's existing BDD runner - ATDD lives or dies by adoption, and forcing a runner switch alongside test-first authoring stalls both. Use the team's incumbent runner (Cucumber-JVM, Behave, or Reqnroll). Pick a new runner only when no incumbent exists; in that case default to the runner matching the production stack's primary language (JVM → Cucumber-JVM, Python → Behave, .NET → Reqnroll).

# Cucumber-JVM
mvn test -Dcucumber.filter.tags='@AC-1.1 or @AC-1.2 or @AC-1.3 or @AC-1.4 or @AC-1.5'

# Behave
behave [email protected] [email protected] [email protected] [email protected] [email protected]

# Reqnroll
dotnet test --filter "Category=AC-1.1|Category=AC-1.2|..."

Anti-patterns

Anti-pattern	Why it fails	Fix
Tests written after implementation	Defeats ATDD; tests verify what was built, not what was asked.	Test-first; tests precede implementation.
Tests without @AC-X.Y tag	No traceability; story acceptance unverifiable.	Tag every Scenario (Step 2).
One mega-scenario covering all ACs	Failure mid-scenario doesn't pinpoint which AC failed.	One Scenario per AC (Step 2).
Auto-generated step bodies that pass silently	Tests appear green; production code never runs.	NotImplementedError (Step 5).
Skipping the AC-to-test artifact	Compliance / audit gap.	Generate per Step 6 each release.
AC tests in the same suite as unit tests	Mixed feedback; harder to interpret.	Separate features/acceptance/ suite.

Limitations

• Requires the team to write ACs first. Doesn't apply to teams without explicit AC artifacts.
• AC quality drives test quality. Vague AC → vague test (or many implicit-precondition flags per gherkin-from-stories Step 5).
• Doesn't replace lower-layer tests. ATDD covers the AC layer; unit / integration coverage still needed for non-AC logic.

References

• acceptance-criteria-extractor - upstream: emits the AC this skill consumes.
• gherkin-from-stories - sibling: story-first variant.
• bdd-step-library-curator - step library this skill draws from + adds to.
• cucumber-testing, behave-testing, reqnroll-testing - runners.
• definition-of-done - DoD that requires AC tests to pass.
• ISTQB Glossary V4.7.1 - https://glossary.istqb.org/en_US/term/acceptance-test-driven-development defines ATDD as "a collaboration-based test-first approach."