Test Pyramid
A guideline for how a healthy test suite should be shaped: many fast, cheap unit tests at the base, fewer integration tests in the middle, and very few slow, expensive end-to-end tests at the top.
Think of it like
Like a nutrition pyramid for a codebase's tests — mostly the fast, cheap staples, with the slow, expensive ones used sparingly at the top.
Junior or senior?
Junior sounds like
Isn't aware their team's test suite has become an inverted pyramid.
Senior sounds like
Can describe a suite that violated it — too many slow E2E tests — and what that cost the team, and how they fixed it.
Ask them
“Has your team's test suite ever turned into an inverted pyramid — too many slow E2E tests? What did that cost you, and how did you fix it?”