The 6 Testing Levels

Level 1: Unit/Logic Tests

Level 2: DOM-based Component Tests

Level 3: Build Output Verification

Level 4: E2E Browser Tests

Level 5: Deterministic + Visual Verification

Level 6: AI-Based Visual Verification

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The 6 Testing Levels

Level 1: Unit/Logic Tests

Level 2: DOM-based Component Tests

Level 3: Build Output Verification

Level 4: E2E Browser Tests

Level 5: Deterministic + Visual Verification

Level 6: AI-Based Visual Verification

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Testing Levels

In this section

Testing Levels

Introduction to the six testing levels for frontend verification.

Introduction to the six testing levels for frontend verification.

In this section

The 6 Testing LevelsIntroduction to the six testing levels for frontend verification.Level 1: Unit/Logic TestsPure JavaScript testing with vitest or jest for logic, data transforms, and state.Level 2: DOM-based Component TestsComponent testing with jsdom or happy-dom and Testing Library.Level 3: Build Output VerificationTesting built files, SSG output, templates, and bundler configuration.Level 4: E2E Browser TestsEnd-to-end testing with Playwright and headless browser verification.Level 5: Deterministic + Visual VerificationCombining computed style checks with visual screenshots for maximum coverage.Level 6: AI-Based Visual VerificationFinal-resort tier — AI judges whether a problem is resolved when neither L4 nor L5 can reach the assertion.

The 6 Testing Levels

Revision History

Takeshi TakatsudoCreated: 2026-04-04T07:11:52+09:00Updated: 2026-06-17T02:21:12+09:00

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