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React Native SSH SFTP is tested in tiers. Each tier answers a different question, runs in a different place, and has a different cost.

Unit tests

Fast Vitest tests for the TypeScript API in src/sshclient.ts, with the native bridge mocked. These are the confidence core.

Integration fixture

A Dockerized OpenSSH server plus a Node smoke test that proves real SSH and SFTP work against a predictable target.

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Unit tests

The unit suite drives the SSHClient class in a plain Node process. It covers the connection factories, platform dispatch, command execution, the shell lifecycle, the full SFTP surface, transfer counters, event routing, and disconnect cleanup. Run them: 
npm test              # run once
npm run test:watch    # re-run on change
npm run test:coverage # run with a coverage report and thresholds

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How the react-native mock works

src/sshclient.ts imports from react-native, a package that only resolves inside a React Native runtime. For unit tests, vitest.config.ts aliases react-native to a hand-written stub at test/mocks/react-native.ts. The stub exposes exactly what the class touches:
  • NativeModules.RNSSHClient — a mock function per native method, so each test steers a call down its success or error path.
  • NativeEventEmitter / DeviceEventEmitter — backed by a shared listener store so a test can emit native events and assert routing.
  • Platform — a mutable OS you can flip between ios and android.
Because Vite resolves the alias and a relative import to the same file, tests import the mock’s helpers directly and share the exact instance the class under test uses.
The real native bridge always invokes callbacks asynchronously. The test helpers in test/unit/support.ts mirror this by deferring callbacks onto a microtask, which keeps patterns like const client = new SSHClient(..., cb => resolve(client)) working correctly.

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Adding a unit test

1

Create a test file

Add a *.test.ts file under test/unit/.
2

Import the class and the mock

Import SSHClient from ../../src/sshclient and the helpers from ../mocks/react-native and ./support.
3

Reset between tests

Call resetMocks() in a beforeEach so listeners and mock state do not leak between cases.
4

Drive a native call

Set an implementation with resolveNative(...) or rejectNative(...), invoke the method, and assert the resolved value, the rejection, and the arguments forwarded to the native mock.

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Coverage expectations

Coverage runs on the v8 provider and enforces global thresholds set in vitest.config.ts. A commit or CI run fails if coverage drops below the floor, so new code should arrive with tests. Raise the thresholds as coverage grows rather than lowering them to fit a change.

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Integration fixture

The integration harness lives in test/integration/. It brings up a disposable OpenSSH server with Docker and runs a Node smoke test that connects with a standalone client (ssh2), runs a command, and completes an SFTP write, list, and read round-trip. The all-in-one script starts the fixture, runs the test, and tears it down: 
npm run test:integration:local
Or manage the fixture yourself when iterating: 
docker compose -f test/integration/docker-compose.yml up -d
npm run test:integration
docker compose -f test/integration/docker-compose.yml down
Running npm run test:integration without the fixture up makes the smoke test retry briefly and then fail with an actionable message pointing you at the command above, rather than a raw connection error.
The integration smoke test does not exercise src/sshclient.ts. That module depends on the React Native native bridge, which does not exist in a plain Node process. The fixture validates the server target and the shape of a real session; it is the ready-made target for the native end-to-end phase described below.
Connection details are read from the environment with local defaults that match the compose file (SSH_HOST, SSH_PORT, SSH_USER, SSH_PASSWORD, SSH_REMOTE_DIR). See test/integration/README.md for the full table.

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Continuous integration

  • Unit tests run in the Compile package workflow on every push and pull request, across Node 22, 24, and 26, and upload a coverage report.
  • Integration tests run in a separate Integration tests workflow that stands up the OpenSSH fixture, so container flakiness never blocks unit feedback.

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Future work

Two tiers are intentionally deferred. They require a native runtime that Node cannot provide, and each deserves its own design pass.
Test the platform bridges directly: iOS (ios/RNSSHClient.m, SSHClient.m) with XCTest, and Android (RNSshClientModule.java) with JUnit. This would cover logic that lives only in native code, such as JSON serialization of directory listings.
Add an example app and drive it with Detox or Maestro against the Docker OpenSSH fixture. This is the only tier that exercises the full stack — JavaScript API, native bridge, and a real server — end to end.
Last modified on July 4, 2026