What is the full lifecycle of a Jest test?

Understanding the lifecycle prevents surprises around shared state. Registration happens first: the whole file is evaluated, so every describe callback runs and every hook is recorded before any test executes. Only then does Jest run the tests in declaration order within a file.

beforeAll(() => console.log("1 file setup"));

describe("group", () => {
  beforeAll(() => console.log("2 group setup"));
  beforeEach(() => console.log("3 group before"));
  afterEach(() => console.log("5 group after"));
  afterAll(() => console.log("7 group teardown"));

  test("first", () => console.log("4 test one"));
  test("second", () => console.log("6 test two"));
});

Execution order per test

• All beforeEach hooks from the outermost block to the innermost
• The test body, including awaited promises
• All afterEach hooks from the innermost block to the outermost
• afterAll once per describe, after its last test

beforeAll is useful for a database connection or a server that is expensive to start. It is dangerous for mutable state because every test shares the same instance. If a test mutates it, later tests can fail depending on order, which is exactly the kind of coupling isolation should prevent.