Can you explain the concept of the testing pyramid and its structure?

The testing pyramid is a concept that describes the optimal ratio of different types of tests in a project to effectively ensure quality.

It consists of three levels:

1. Unit tests — based on testing individual functions or components. They are fast, isolated, and cover low-level logic. There should be the most of them.

2. Integration tests — check the interaction between multiple components or modules. They are more complex and slower than unit tests.

3. E2E tests (End-to-End tests) — simulate user behavior and test the entire system. They are the slowest and most fragile, so there should be the fewest of them.

In the end, the pyramid looks like this:

    E2E
  Integration
Unit tests

This approach helps quickly identify errors early and reduces testing time.