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Digital Garden

Testing Pyramid

serhiismetanskyi/digital-garden

Testing Pyramid

Practical reference for test levels, tooling, and strategy. Based on: The Testing Pyramid: Everybody Knows It, Nobody Follows It

The Pyramid

        ▲
       /E2E\        few — critical user flows only
      /─────\
     /       \
    / Integra-\     moderate — component interactions, API contracts
   /  tion     \
  /─────────────\
 /               \
/   Unit Tests    \  many — all business logic, validation, edge cases
/─────────────────\

Layer	Speed	Count	Tool
Unit	0.001–0.01 s	Thousands	pytest
Integration	0.1–1 s	Hundreds	pytest + Playwright APIRequestContext
E2E	5–30 s	Tens	Playwright (browser)

Sections

1. Unit Tests

File	Topics
Concept & Examples	Isolation, fast feedback, pytest marks, coverage, typing
Common Mistakes	Missing assertions, hidden dependencies, no isolation

2. Integration Tests

File	Topics
Concept & Examples	Real HTTP via Playwright APIRequestContext, fixtures, cleanup
Common Mistakes	Shared state, test-order dependence, over-mocking

3. E2E Tests

File	Topics
Concept & Examples	Browser automation with Playwright, stable locators, user flows
Common Mistakes	Fragile selectors, no auto-wait, testing every validation E2E

4. Pyramid Strategy

File	Topics
Shape, Anti-Patterns & Alternatives	Ice cream cone, Testing Trophy, microservice contracts, CI timing

Quick Decision Guide

What you need to test	Level
Single function, validation rule, calculation	Unit
API endpoint → database round trip	Integration
Service A calls Service B	Integration
User completes a full workflow in browser	E2E
Field-level form validation in the UI	Unit (not E2E)
Auth contract between two services	Integration (contract)

Anti-Pattern: Ice Cream Cone

/─────────────────\
/   E2E (many!)    \  ← slow, flaky, 40+ min CI
/─────────────────\
     /       \
    / Integra-\     ← almost none
   /  tion     \
  /─────────────\
       /  \
      /Unit\         ← barely any
     /──────\

Happens when teams skip unit and integration tests during development and try to cover everything with Playwright at the end.

See also