Effective test cases are clear, comprehensive, and maintainable.
Structure:
- ID: unique identifier (TC-101).
- Title: brief description.
- Module / feature: what's being tested.
- Pre-conditions: state before testing.
- Test data: specific values needed.
- Steps: numbered, specific actions.
- Expected results: what should happen.
- Actual results: filled during execution.
- Status: Pass / Fail / Blocked.
- Severity / Priority: importance.
Principles:
1. Specific and observable.
- "User clicks Save button" — clear.
- "User makes changes" — vague.
2. One thing per test.
- Single objective.
- Easier to debug failures.
3. Cover happy path AND edge cases.
- Standard flow.
- Boundaries (max field length, zero values).
- Negative cases (invalid input).
- Concurrency (multiple users).
- Error scenarios.
4. Independent.
- Tests don't depend on each other.
- Each can run in isolation.
5. Repeatable.
- Same input -> same output.
- Test data created/cleaned within test.
6. Maintainable.
- Use shared resources (test data factories).
- Don't duplicate logic.
- Update as features evolve.
7. Use Gherkin / Given-When-Then format for behavior:
Given a Lead with Status = Working When user clicks Convert Lead Then Account, Contact, Opportunity are created And Lead Status = Converted
Readable for business stakeholders too.
Coverage strategy:
- Equivalence partitioning — group similar inputs.
- Boundary value analysis — test edges (0, 1, max-1, max).
- State transitions — test all stage transitions.
- Error guessing — based on experience.
- Use case scenarios — end-to-end paths.
Common pitfalls:
- Vague test cases — "test login" tells you nothing.
- Massive test cases — 50 steps, hard to debug.
- No expected results — "user does something" without expected outcome.
- Outdated test cases — system changed; test wasn't updated.
Senior QA insight: good test cases are documentation. Future testers should be able to execute without prior knowledge.
The senior framing: writing test cases is harder than executing them. Investment in good test cases pays back across many runs.