The Test Pyramid vs The Ice Cream Cone

The Ideal (The Pyramid)

Proposed by tracking Mike Cohn.

• 70% Unit Tests: Fast (ms). Deterministic. Cheap.
• 20% Integration: Test db/api boundaries. Slower (s).
• 10% E2E (UI): Test user flows. Slow (m). Flaky. Expensive.

The Reality (The Ice Cream Cone)

Most organizations have:

• 0% Unit: "Too hard to mock things."
• 10% Integration: "We don't have environments."
• 90% E2E (Selenium/Cypress): "Just record what the user does."

Why The Cone Kills Velocity

1. Flakiness: E2E tests fail 10% of the time due to network bloops, not bugs.
2. Duration: A suite of 500 Selenium tests takes 4 hours. Developers stop running them.
3. Debugging: When an E2E test fails, you know "It didn't click the button," but you don't know why.

The Fix: Invert the Pyramid

Delete your E2E tests.

• Radical? Yes.
• If a test is flaky, it provides negative value. It erodes trust.
• Replace 1 E2E test with 20 Unit tests and 2 Integration tests.