What is the difference between initialization using Before All and Before Each in test frameworks?

Before All and Before Each are hooks (functions) that run before tests, but with different scopes:

• Before All (for example, beforeAll in Jest) runs once before all tests in a suite. It is used for initializing shared resources that can be reused across all tests.

• Before Each (for example, beforeEach) runs before each individual test. It is used to prepare a clean state before each test so that tests do not affect each other.

Example:

beforeAll(() => {
  // Runs once
  initializeDatabaseConnection();
});

beforeEach(() => {
  // Runs before each test
  resetTestData();
});