Integration and E2E Testing Principles Skill

Integration and E2E Testing Principles

Test Type Definition and Limits

| Test Type | Purpose | Scope | Limit per Feature | Implementation Timing | |-----------|---------|-------|-------------------|----------------------| | Integration | Verify component interactions | Partial system integration | MAX 3 | Created alongside implementation | | E2E | Verify critical user journeys | Full system | MAX 1-2 | Executed in final phase only |

Behavior-First Principle

Include (High ROI)

Business logic correctness (calculations, state transitions, data transformations)
Data integrity and persistence behavior
User-visible functionality completeness
Error handling behavior (what user sees/experiences)

Exclude (Low ROI in CI/CD)

External service real connections → Use contract/interface verification
Performance metrics → Non-deterministic, defer to load testing
Implementation details → Focus on observable behavior
UI layout specifics → Focus on information availability

Principle: Test = User-observable behavior verifiable in isolated CI environment

ROI Calculation

ROI Score = (Business Value × User Frequency + Legal Requirement × 10 + Defect Detection)
            / (Creation Cost + Execution Cost + Maintenance Cost)

Cost Table

| Test Type | Create | Execute | Maintain | Total | |-----------|--------|---------|----------|-------| | Unit | 1 | 1 | 1 | 3 | | Integration | 3 | 5 | 3 | 11 | | E2E | 10 | 20 | 8 | 38 |

Test Skeleton Specification

Required Comment Patterns

Each test MUST include the following annotations:

// AC: [Original acceptance criteria text]
// Behavior: [Trigger] → [Process] → [Observable Result]
// @category: core-functionality | integration | edge-case | e2e
// @dependency: none | [component names] | full-system
// @complexity: low | medium | high
// ROI: [score]

Verification Items (Optional)

When verification points need explicit enumeration:

// Verification items:
// - [Item 1]
// - [Item 2]

EARS Format Mapping

| EARS Keyword | Test Type | Generation Approach | |--------------|-----------|---------------------| | When | Event-driven | Trigger event → verify outcome | | While | State condition | Setup state → verify behavior | | If-then | Branch coverage | Both condition paths verified | | (none) | Basic functionality | Direct invocation → verify result |

Test File Naming Convention

Integration tests: *.int.test.* or *.integration.test.*
E2E tests: *.e2e.test.*

The test runner or framework in the project determines the appropriate file extension.

Review Criteria

Skeleton and Implementation Consistency

| Check | Failure Condition | |-------|-------------------| | Behavior Verification | No assertion for "observable result" in skeleton | | Verification Item Coverage | Listed items not all covered by assertions | | Mock Boundary | Internal components mocked in integration test |

Implementation Quality

| Check | Failure Condition | |-------|-------------------| | AAA Structure | Arrange/Act/Assert separation unclear | | Independence | State sharing between tests, order dependency | | Reproducibility | Date/random dependency, varying results | | Readability | Test name doesn't match verification content |

Agent Skills: Integration and E2E Testing Principles

Skill Files