Use newer TestTrack APIs

[rzane]

This PR migrates from TestTrack's v1 APIs to the v4 APIs, which require app versioning information. This allows TestTrack to serve split configurations specific to each build of your application.

load

Fetches visitor config from the server to create a TestTrack instance.

import { load, createCookieStorage } from '@betterment-oss/test-track';

const testTrack = await load({
  client: {
    url: 'https://testtrack.example.com',
    appName: 'my-app',
    appVersion: '0.0.0',
    buildTimestamp: import.meta.env.TT_BUILD_TIMESTAMP
  },
  storage: createCookieStorage({ name: 'tt_visitor_id', domain: '.example.com' })
});

create

Creates a TestTrack instance with preloaded data (e.g., server-rendered).

import { create, createCookieStorage } from '@betterment-oss/test-track';

const testTrack = create({
  client: {
    url: 'https://testtrack.example.com',
    appName: 'my-app',
    appVersion: '0.0.0',
    buildTimestamp: import.meta.env.TT_BUILD_TIMESTAMP
  },
  storage: createCookieStorage({ name: 'tt_visitor_id', domain: '.example.com' }),
  visitorConfig: { visitor: { id: '...', assignments: [...] }, splits: [...] }
});

initialize (Deprecated)

Uses window.TT for configuration. Use load or create instead.

import { initialize } from '@betterment-oss/test-track';

const testTrack = initialize({
  client: {
    appName: 'my-app',
    appVersion: '0.0.0',
    buildTimestamp: import.meta.env.TT_BUILD_TIMESTAMP
  }
});

Breaking changes:

• Now requires a client option with appName, appVersion, and buildTimestamp
• Now synchronous (returns TestTrack instead of Promise<TestTrack>)

API Endpoints

• GET /api/v4/apps/:app/versions/:version/builds/:build/visitors/:id/config replaces GET /api/v1/visitors/:id
• POST /api/v4/apps/:app/versions/:version/builds/:build/identifier replaces POST /api/v1/identifier
• POST /api/v2/visitors/:id/assignment_overrides replaces POST /api/v1/assignment_override
• Request bodies are now JSON instead of form-encoded. This means POST requests to the Test Track API will run a preflight request. See: Relax CORS allowed headers testtrack-cli#69.

Type Changes

• logIn and signUp now accept value as a string instead of number

Vite Plugin

Provides import.meta.env.TT_BUILD_TIMESTAMP.

import { testTrackPlugin } from '@betterment-oss/test-track/vite';

export default defineConfig({
  plugins: [testTrackPlugin()]
});

[samandmoore]

domainlgtm

[samandmoore]

platformlgtm too

sorry it took me a while to review this!