tanstack-router-testing

Unit testing utilities for TanStack Router and TanStack Start.

Quick start

pnpm add -D @tanstack-router-testing/react-router-testing @tanstack-router-testing/react-start-testing

Configure Vitest with the Start shim:

// vitest.config.ts
import { tanstackStartTesting } from '@tanstack-router-testing/react-start-testing/vite';
import { defineConfig } from 'vitest/config';

export default defineConfig({
  plugins: [tanstackStartTesting()],
  test: { environment: 'jsdom' },
});

Write your first test — import a single route file, pass it to the harness, and assert:

// posts.$postId.test.tsx
import { render } from '@testing-library/react';
import { describe, expect, it } from 'vitest';
import { createRouterHarness } from '@tanstack-router-testing/react-router-testing';
import { Route } from './routes/posts.$postId';

describe('post route', () => {
  it('loads and renders a post', async () => {
    const harness = createRouterHarness({
      route: Route,
      params: { postId: '42' }, // fully typed from route path
      loaderData: { id: '42', title: 'Hello' }, // skip the real loader
    });
    await harness.load();
    const { findByText } = render(<harness.TestRouterProvider />);
    await expect(findByText('Hello')).resolves.toBeTruthy();
    harness.cleanup();
  });
});

Or use a full route tree for integration-level tests:

import { createRouterHarness } from '@tanstack-router-testing/react-router-testing';
import { routeTree } from './routeTree.gen';

const harness = createRouterHarness({ routeTree, initialEntries: ['/posts/7'] });
await harness.load();
expect(harness.getLoaderData('/posts/$postId')).toBeDefined();
harness.cleanup();

Packages

Package	Purpose
react-router-testing	createRouterHarness (file route or full tree, with per-route overrides), createTestRouter, SSR harness
react-start-testing	mockServerFn, mockMiddleware, renderRoute, createStartTestRuntime, RSC runtime, Vite plugin
router-testing-core	Internal registry/env runtime (transitive dependency)

All packages are scoped under @tanstack-router-testing/.

Design principles

1. Real router, not route stubs. Tests exercise createRouter, route trees, memory history, loaders, guards, params, search, and redirects through the router itself.
2. Production-shaped Start calls. Server functions are called as await fn({ data }) — the harness supplies mocks and leaves the call shape alone.
3. Upstream-mergeable shape. Public exports are shaped for future first-party subpaths (@tanstack/react-router/testing).

Documentation

• Getting Started
• API Reference
• Guides: Loaders | Guards & Redirects | Server Functions | Middleware | SSR | RSC | Query Integration
• Example Tests

Running tests

pnpm run build              # build all packages
pnpm test:unit:core         # fast core + integration tests
pnpm test:types             # type-level assertions
pnpm test:unit:vendored     # 110 vendored TanStack app smoke tests
pnpm run lint:check         # oxlint + oxfmt

Contributing

This project aims to become an upstream contribution to tanstack/router. Feedback, issues, and PRs welcome.

License

MIT