SFTP Testing API

Mock SFTP and FTP clients for Jest testing without real servers.

What It Does

The SFTP Testing API provides in-memory mock implementations of ssh2-sftp-client and basic-ftp libraries for testing SFTP/FTP functionality without requiring actual server connections. It enables fast, reliable, deterministic tests with a simple one-line setup.

Key Capabilities

• Dual Protocol Mocking: Both SFTP and FTP support
• In-Memory File System: Fast, deterministic tests
• Jest Integration: Automatic mocking with fock() function
• Stream Support: Bidirectional stream handling
• File Operations: Upload, download, list, delete
• Directory Navigation: Full hierarchical directory support
• Test Isolation: Easy file system reset between tests

Main Component

fock() Function

const client = fock()
client.add('/test/file.txt', Buffer.from('content'))
client.clearFiles()

Sets up mocks for both ssh2-sftp-client and basic-ftp.

MockClient (SFTP)

Mock implementation of ssh2-sftp-client:

• connect(), end(): Connection management
• list(path): Directory listing
• get(path): File download
• put(input, path): File upload
• delete(path): File deletion
• cwd(): Current working directory

MockFtpClient (FTP)

Mock implementation of basic-ftp:

• connect(), access(), login(): Connection
• pwd(): Print working directory
• list(path): Directory listing
• size(path): File size
• uploadFrom(source, dest): Upload
• download(dest, source): Download
• remove(path): Delete

InternalFileSystem

Core in-memory file system:

• Hierarchical directory structure
• Buffer and file path storage
• Stream conversion
• Path navigation (absolute, relative, ., ..)

Usage Example

import {fock} from '@engineering11/sftp-testing'
 
describe('SFTP Operations', () => {
  const client = fock()
 
  beforeEach(() => {
    client.add('/data/file1.txt', Buffer.from('test'))
    client.add('/data/file2.csv', './test-data/sample.csv')
  })
 
  afterEach(() => {
    client.clearFiles()
  })
 
  it('should list files', async () => {
    const sftpClient = new SFTPClient()
    await sftpClient.connect({...})
    const files = await sftpClient.list('/data')
    expect(files).toHaveLength(2)
  })
})

Common Use Cases

• Testing SFTP upload/download logic
• Testing FTP client integrations
• Testing file processing pipelines
• Unit testing without external dependencies
• Integration testing for file transfer

What Customers Don’t Have to Build

• Mock SFTP server
• Mock FTP server
• In-memory file system
• Stream handling mocks
• Jest mocking configuration
• File metadata generation
• Directory navigation logic
• Test isolation infrastructure