launchdarkly-testing

npm install --save-dev launchdarkly-node-server-sdk
pip install launchdarkly-server-sdk

import * as LaunchDarkly from 'launchdarkly-node-server-sdk';

const td = LaunchDarkly.TestData.dataSource();
const client = LaunchDarkly.init('sdk-test-key', {
  updateProcessor: td,
  sendEvents: false,         // No event uploads in tests
});

await client.waitForInitialization();

// Configure a flag's default + per-user variation
td.update(td.flag('show-new-ui').booleanFlag().on(true));

test('flag on returns true', async () => {
  td.update(td.flag('show-new-ui').booleanFlag().on(true));
  const user = { key: 'user-1' };
  const enabled = await client.variation('show-new-ui', user, false);
  expect(enabled).toBe(true);
});

test('flag off returns default', async () => {
  td.update(td.flag('show-new-ui').booleanFlag().on(false));
  const enabled = await client.variation('show-new-ui', { key: 'user-1' }, false);
  expect(enabled).toBe(false);
});

test('only premium users get treatment', async () => {
  td.update(
    td.flag('premium-feature')
      .booleanFlag()
      .variationForUser('premium-user-1', true)
      .fallthroughVariation(false)
  );
  expect(await client.variation('premium-feature', { key: 'premium-user-1' }, false)).toBe(true);
  expect(await client.variation('premium-feature', { key: 'free-user-1' }, false)).toBe(false);
});

test('rollout is deterministic per user', async () => {
  td.update(td.flag('half-rollout').booleanFlag().on(true).variations(true, false));
  // Bucketing is deterministic on user key
  const r1 = await client.variation('half-rollout', { key: 'user-1' }, false);
  const r2 = await client.variation('half-rollout', { key: 'user-1' }, false);
  expect(r1).toBe(r2);
});

const fileSource = LaunchDarkly.FileDataSource({
  paths: ['./tests/fixtures/ld-flags.json'],
});
const client = LaunchDarkly.init('sdk-test-key', {
  updateProcessor: fileSource,
  sendEvents: false,
});

afterAll(async () => {
  await client.close();
});

npm test

jobs:
  ld-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-node@v4
      - run: npm ci && npm test