Testing Strategies
Approaches and testing levels for validating software works correctly, from unit tests to end-to-end tests and testing in production.
What it is
Testing strategies define what types of tests to write, how many, and how to organize them to maximize code confidence with the lowest maintenance cost.
Testing pyramid
/\ E2E (few, slow, fragile)
/ \
/----\ Integration (some)
/ \
/--------\ Unit (many, fast, stable)
Test types
| Type | What it tests | Speed | Fragility |
|---|---|---|---|
| Unit | Isolated function/class | Very fast | Low |
| Integration | Components together | Medium | Medium |
| E2E | Complete user flow | Slow | High |
| Contract | APIs between services | Fast | Low |
Approaches
| Approach | Mechanism | When to use |
|---|---|---|
| TDD | Write test before code | Business logic, algorithms |
| BDD | Tests as behavior specifications | User requirements, acceptance |
| Property-based | Generate random inputs, verify invariants | Parsers, serialization, edge cases |
| Snapshot | Compare output with saved version | UI components, API responses |
Testing in production
- Feature flags for gradual rollout
- Canary deployments
- Observability to detect problems
Why it matters
An effective testing strategy balances speed, coverage, and confidence. Too many unit tests without integration give false security. Too many e2e tests are slow and brittle. The testing pyramid provides the framework for finding the right balance.
References
- Testing Trophy — Kent C. Dodds.
- The Practical Test Pyramid — Ham Vocke, 2018. Practical guide to the testing pyramid.
- Testing Library — Testing Library, 2024. User-centered testing tools.
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