What types of tests have you created and used in your projects?

In Node.js projects, I have created and used several types of tests:

• Unit tests — test individual functions or modules in isolation. For example, testing a data processing function.
• Integration tests — test the interaction between modules or with external services, such as database operations.
• E2E (end-to-end) tests — test the entire application, simulating user actions.

Here's a simple example of a unit test using Jest:

const sum = (a, b) => a + b;

test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});