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
code
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:
code
// 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:
code
// 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 |
Quality Standards
Required
- •Each test verifies one behavior
- •Clear AAA (Arrange-Act-Assert) structure
- •No test interdependencies
- •Deterministic execution
Prohibited
- •Testing implementation details
- •Multiple behaviors per test
- •Shared mutable state
- •Time-dependent assertions without mocking