Test Run Lifecycle

Understanding the test run lifecycle is essential for writing effective tests, debugging issues, and optimizing your test suite. This guide explains when and in what order different lifecycle phases occur in Vitest, from initialization to teardown.

Overview

A typical Vitest test run goes through these main phases:

1. Initialization - Configuration loading and project setup
2. Global Setup - One-time setup before any tests run
3. Worker Creation - Test workers are spawned based on the pool configuration
4. Test File Collection - Test files are discovered and organized
5. Test Execution - Tests run with their hooks and assertions
6. Reporting - Results are collected and reported
7. Global Teardown - Final cleanup after all tests complete

Phases 4–6 run once for each test file, so across your test suite they will execute multiple times and may also run in parallel across different files when you use more than 1 worker.

Detailed Lifecycle Phases

1. Initialization Phase

When you run vitest, the framework first loads your configuration and prepares the test environment.

What happens:

• Command-line arguments are parsed
• Configuration file is loaded
• Project structure is validated

This phase can run again if the config file or one of its imports changes.

Scope: Main process (before any test workers are created)

2. Global Setup Phase

If you have configured globalSetup files, they run once before any test workers are created.

What happens:

• setup() functions (or exported default function) from global setup files execute sequentially
• Multiple global setup files run in the order they are defined

Scope: Main process (separate from test workers)

Important notes:

• Global setup runs in a different global scope from your tests
• Tests cannot access variables defined in global setup (use provide/inject instead)
• Global setup only runs if there is at least one test queued

globalSetup.ts

export function setup(project) {
  // Runs once before all tests
  console.log('Global setup')

  // Share data with tests
  project.provide('apiUrl', 'http://localhost:3000')
}

export function teardown() {
  // Runs once after all tests
  console.log('Global teardown')
}

3. Worker Creation Phase

After global setup completes, Vitest creates test workers based on your pool configuration.

What happens:

• Workers are spawned according to the browser.enabled or pool setting (threads, forks, vmThreads, or vmForks)
• Each worker gets its own isolated environment (unless isolation is disabled)
• By default, workers are not reused to provide isolation. Workers are reused only if:
  • isolation is disabled
  • OR pool is vmThreads or vmForks because VM provides enough isolation

Scope: Worker processes/threads

4. Test File Setup Phase

Before each test file runs, setup files are executed.

What happens:

• Setup files run in the same process as your tests
• By default, setup files run in parallel (configurable via sequence.setupFiles)
• Setup files execute before each test file
• Any global state or configuration can be initialized here

Scope: Worker process (same as your tests)

Important notes:

• If isolation is disabled, setup files still rerun before each test file to trigger side effects, but imported modules are cached
• Editing a setup file triggers a rerun of all tests in watch mode

setupFile.ts

import { afterEach } from 'vitest'

// Runs before each test file
console.log('Setup file executing')

// Register hooks that apply to all tests
afterEach(() => {
  cleanup()
})

5. Test Collection and Execution Phase

This is the main phase where your tests actually run.

Test File Execution Order

Test files are executed based on your configuration:

• Sequential by default within a worker
• Files will run in parallel across different workers, configured by maxWorkers
• Order can be randomized with sequence.shuffle or fine-tuned with sequence.sequencer
• Long-running tests typically start earlier (based on cache) unless shuffle is enabled

Within Each Test File

The execution follows this order:

1. File-level code - All code outside describe blocks runs immediately
2. Test collection - describe blocks are processed, and tests are registered as side effects of importing the test file
3. beforeAll hooks - Run once before any tests in the suite
4. For each test:
   • beforeEach hooks execute (in order defined, or based on sequence.hooks)
   • Test function executes
   • afterEach hooks execute (reverse order by default with sequence.hooks: 'stack')
   • onTestFinished callbacks run (always in reverse order)
   • If test failed: onTestFailed callbacks run
   • Note: if repeats or retry are set, all of these steps are executed again
5. afterAll hooks - Run once after all tests in the suite complete

Example execution flow:

// This runs immediately (collection phase)
console.log('File loaded')

describe('User API', () => {
  // This runs immediately (collection phase)
  console.log('Suite defined')

  beforeAll(() => {
    // Runs once before all tests in this suite
    console.log('beforeAll')
  })

  beforeEach(() => {
    // Runs before each test
    console.log('beforeEach')
  })

  test('creates user', () => {
    // Test executes
    console.log('test 1')
  })

  test('updates user', () => {
    // Test executes
    console.log('test 2')
  })

  afterEach(() => {
    // Runs after each test
    console.log('afterEach')
  })

  afterAll(() => {
    // Runs once after all tests in this suite
    console.log('afterAll')
  })
})

// Output:
// File loaded
// Suite defined
// beforeAll
// beforeEach
// test 1
// afterEach
// beforeEach
// test 2
// afterEach
// afterAll

Nested Suites

When using nested describe blocks, hooks follow a hierarchical pattern:

describe('outer', () => {
  beforeAll(() => console.log('outer beforeAll'))
  beforeEach(() => console.log('outer beforeEach'))

  test('outer test', () => console.log('outer test'))

  describe('inner', () => {
    beforeAll(() => console.log('inner beforeAll'))
    beforeEach(() => console.log('inner beforeEach'))

    test('inner test', () => console.log('inner test'))

    afterEach(() => console.log('inner afterEach'))
    afterAll(() => console.log('inner afterAll'))
  })

  afterEach(() => console.log('outer afterEach'))
  afterAll(() => console.log('outer afterAll'))
})

// Output:
// outer beforeAll
// outer beforeEach
// outer test
// outer afterEach
// inner beforeAll
// outer beforeEach
// inner beforeEach
// inner test
// inner afterEach (with stack mode)
// outer afterEach (with stack mode)
// inner afterAll
// outer afterAll

Concurrent Tests

When using test.concurrent or sequence.concurrent:

• Tests within the same file can run in parallel
• Each concurrent test still runs its own beforeEach and afterEach hooks
• Use test context for concurrent snapshots: test.concurrent('name', async ({ expect }) => {})

6. Reporting Phase

Throughout the test run, reporters receive lifecycle events and display results.

What happens:

• Reporters receive events as tests progress
• Results are collected and formatted
• Test summaries are generated
• Coverage reports are generated (if enabled)

For detailed information about the reporter lifecycle, see the Reporters guide.

7. Global Teardown Phase

After all tests complete, global teardown functions execute.

What happens:

• teardown() functions from globalSetup files run
• Multiple teardown functions run in reverse order of their setup
• In watch mode, teardown runs before process exit, not between test reruns

Scope: Main process

globalSetup.ts

export function teardown() {
  // Clean up global resources
  console.log('Global teardown complete')
}

Lifecycle in Different Scopes

Understanding where code executes is crucial for avoiding common pitfalls:

Phase	Scope	Access to Test Context	Runs
Config File	Main process	❌ No	Once per Vitest run
Global Setup	Main process	❌ No (use provide/inject)	Once per Vitest run
Setup Files	Worker (same as tests)	✅ Yes	Before each test file
File-level code	Worker	✅ Yes	Once per test file
beforeAll / afterAll	Worker	✅ Yes	Once per suite
beforeEach / afterEach	Worker	✅ Yes	Per test
Test function	Worker	✅ Yes	Once (or more with retries/repeats)
Global Teardown	Main process	❌ No	Once per Vitest run

Watch Mode Lifecycle

In watch mode, the lifecycle repeats with some differences:

1. Initial run - Full lifecycle as described above
2. On file change:
   • New test run starts
   • Only affected test files are re-run
   • Setup files run again for those test files
   • Global setup does not re-run (use project.onTestsRerun for rerun-specific logic)
3. On exit:
   • Global teardown executes
   • Process terminates

Performance Considerations

Understanding the lifecycle helps optimize test performance:

• Global setup is ideal for expensive one-time operations (database seeding, server startup)
• Setup files run before each test file - avoid heavy operations here if you have many test files
• beforeAll is better than beforeEach for expensive setup that doesn't need isolation
• Disabling isolation improves performance, but setup files still execute before each file
• Pool configuration affects parallelization and available APIs

For tips on how to improve performance, read the Improving Performance guide.

Related Documentation

• Global Setup Configuration
• Setup Files Configuration
• Test Sequencing Options
• Isolation Configuration
• Pool Configuration
• Extending Reporters - for reporter lifecycle events
• Test API Reference - for hook APIs and test functions