useForm fails with "React is null" during tests using Vitest (React 19 + Vite)

[felipecoders]

Issue Summary

I'm building a React library using Vite that simplifies and automates the creation of forms. Everything works as expected during development and production builds — the library builds successfully and functions correctly when consumed.

However, when writing unit tests using Vitest, I encounter the following runtime error inside one of my custom hooks:

Example Code

import { z } from 'zod';
import { useForm } from 'react-hook-form';

export function useCustomForm<T>() {
  const methods = useForm<z.infer<T>>({ /* ... */ });
  //                          ^ Cannot read properties of null (reading 'useRef')
}

Error

TypeError: Cannot read properties of null (reading 'useRef')

This only happens when running tests — not during build or runtime usage of the library.

package.json

{
  "dependencies": {
    "react-hook-form": "^7.55.0"
  },
  "devDependencies": {
    "@testing-library/jest-dom": "^6.6.3",
    "@testing-library/react": "^16.3.0",
    "@vitejs/plugin-react": "4.3.4"
  },
  "peerDependencies": {
    "react": "19.0.0",
    "react-dom": "19.0.0"
  }
}

Notes

• The error seems related to how useForm() accesses React.useRef, but only fails during tests.
• I’m using react@19.0.0, which is correctly declared as a peer dependency.
• Everything works perfectly outside the test environment.

Question

Is this a known compatibility issue with React 19 or Vitest?
Is there any specific setup required for testing react-hook-form under this configuration?

Thanks in advance for your help!

[felipecoders]

Closed: The issue was related to React Hook Form's context. I needed to create a subcomponent directly in the test to wrap the useForm call, even though it was already used inside another component. This resolved the error.