docs: Testing & Mocking

Author: unnoq

apps/content/.vitepress/config.ts

@@ -211,11 +211,11 @@ export default withMermaid(defineConfig({
             { text: 'Building Custom Plugins', link: '/docs/advanced/building-custom-plugins' },
             { text: 'Exceeds the maximum length ...', link: '/docs/advanced/exceeds-the-maximum-length-problem' },
             { text: 'Extend Body Parser', link: '/docs/advanced/extend-body-parser' },
-            { text: 'Mocking', link: '/docs/advanced/mocking' },
             { text: 'Publish Client to NPM', link: '/docs/advanced/publish-client-to-npm' },
             { text: 'RPC JSON Serializer', link: '/docs/advanced/rpc-json-serializer' },
             { text: 'RPC Protocol', link: '/docs/advanced/rpc-protocol' },
             { text: 'SuperJson', link: '/docs/advanced/superjson' },
+            { text: 'Testing & Mocking', link: '/docs/advanced/testing-mocking' },
             { text: 'Validation Errors', link: '/docs/advanced/validation-errors' },
           ],
         },

apps/content/docs/advanced/mocking.md

@@ -0,0 +1,51 @@
+---
+title: Testing & Mocking
+description: How to test and mock oRPC routers and procedures?
+---
+
+# Testing & Mocking
+
+Testing and mocking are essential parts of the development process, ensuring your oRPC routers and procedures work as expected. This guide covers strategies for testing and mocking in oRPC applications.
+
+## Testing
+
+Using [Server-Side Clients](/docs/client/server-side), you can directly invoke your procedures in tests without additional setup. This approach allows you to test procedures in isolation, ensuring they behave correctly.
+
+```ts
+import { call } from '@orpc/server'
+
+it('works', async () => {
+  await expect(
+    call(router.planet.list, { page: 1, size: 10 })
+  ).resolves.toEqual([
+    { id: '1', name: 'Earth' },
+    { id: '2', name: 'Mars' },
+  ])
+})
+```
+
+::: info
+You can also use the [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API) to create production-like clients for testing purposes. [Learn more](/docs/best-practices/optimize-ssr#alternative-approach)
+:::
+
+## Mocking
+
+The [Implementer](/docs/contract-first/implement-contract#the-implementer) is designed for contract-first development, but it can also create alternative versions of your [router](/docs/router) or [procedure](/docs/procedure) for testing.
+
+```ts twoslash
+import { router } from './shared/planet'
+// ---cut---
+import { implement, unlazyRouter } from '@orpc/server'
+
+const fakeListPlanet = implement(router.planet.list).handler(() => [])
+```
+
+You can use `fakeListPlanet` to replace the actual `listPlanet` implementation during tests.
+
+::: info
+The `implement` function is also useful for creating mock servers for frontend testing scenarios.
+:::
+
+::: warning
+The `implement` function doesn't support [lazy routers](/docs/router#lazy-router) yet. Use the `unlazyRouter` utility to convert your lazy router before implementing. [Learn more](/docs/contract-first/router-to-contract#unlazy-the-router)
+:::