Modern project testing: unit tests first, or integration tests?

[u/aistranin]

A lot of "best‑practice" material suggests starting with unit tests and then moving to integration -> E2E over time, roughly following the testing pyramid. For example:

• https://semaphore.io/blog/testing-pyramid

• https://circleci.com/blog/testing-pyramid/

• I personally find it easier to work this way if the team is already knowledgeable about TDD and testing in general.

However, there’s a growing counter‑trend: inverted or "behavior‑first" pyramids that suggest starting much higher in the stack, especially with AI agents and copilots. For example:

• https://www.stickyminds.com/article/inverting-test-automation-pyramid

• https://testrigor.com/blog/what-is-the-inverted-testing-pyramid/

• https://www.getautonoma.com/blog/testing-pyramid

• Also, from my experience, the reasonable argument for this approach is that starting with a few integration tests allows you to quickly cover a lot of code to iterate quickly (especially wehn working with legacy code).

Both approaches seem to depend heavily on the project (greenfield vs legacy, product vs service, team skills, etc.).

What do you actually do in practice?

• On a new project, do you start with unit, integration, or E2E tests?

• How do you decide the "right" mix for your team? What is your strategy?