---

name: testing description: Use when writing or running tests for this project. Covers unit vs E2E test decisions, test file locations, mock patterns, and project-specific testing conventions. (project)

Testing in Sandbox SDK

This skill covers project-specific testing conventions. For TDD methodology, use the superpowers:test-driven-development skill.

Two Test Suites

Unit Tests

When to use: Testing isolated logic, client behavior, service methods, utilities.

Location:

• SDK: packages/sandbox/tests/
• Container: packages/sandbox-container/tests/

Runtime:

• SDK tests run in Workers runtime via @cloudflare/vitest-pool-workers
• Container tests run in Bun runtime

Commands:

npm test                              # All unit tests
npm test -w @cloudflare/sandbox       # SDK tests only
npm test -w @repo/sandbox-container   # Container tests only

Mock patterns:

• SDK tests use a mock container (no Docker needed)
• Container tests mock external dependencies (filesystem, processes)
• Use createNoOpLogger() from @repo/shared for logger mocks

Known issue: SDK unit tests may hang on exit due to vitest-pool-workers workerd shutdown. Tests still pass/fail correctly - the hang is cosmetic.

E2E Tests

When to use: Testing full request flow, container integration, real Docker behavior.

Location: tests/e2e/

Runtime: Real Cloudflare Workers + Docker containers

Commands:

npm run test:e2e                                                    # All E2E tests
npm run test:e2e -- -- tests/e2e/process-lifecycle-workflow.test.ts # Single file
npm run test:e2e -- -- tests/e2e/git-clone-workflow.test.ts -t 'test name'  # Single test

Key patterns:

• All tests share ONE container for performance
• Use unique sessions for test isolation
• Tests run in parallel via thread pool
• Config: vitest.e2e.config.ts (root level)

Writing E2E tests:

import { createTestSession } from './helpers';

describe('Feature X', () => {
  let session: TestSession;

  beforeEach(async () => {
    session = await createTestSession(); // Gets unique session
  });

  it('should do something', async () => {
    const result = await session.sandbox.exec('echo hello');
    expect(result.stdout).toBe('hello\n');
  });
});

When to Use Which

Scenario	Test Type
Client method logic	Unit
Service business logic	Unit
Request/response handling	Unit
Full command execution flow	E2E
File operations with real filesystem	E2E
Process lifecycle (start, stop, signal)	E2E
Port exposure and preview URLs	E2E
Git operations	E2E

Test-Specific Conventions

File naming: *.test.ts for both unit and E2E tests

Test structure:

describe('ComponentName', () => {
  describe('methodName', () => {
    it('should do X when Y', async () => {
      // Arrange
      // Act
      // Assert
    });
  });
});

Assertions: Use vitest's expect() with clear, specific assertions

Running Tests During Development

After making any meaningful code change:

1. npm run check - catch type errors first
2. npm test - verify unit tests pass
3. npm run test:e2e - if touching core functionality

Build trust: The monorepo build system handles dependencies automatically. E2E tests always run against latest built code - no manual rebuild needed.