Why Form Test Fails While Using React Hook Form?

Question

I am using react-hook-form to build a form. The form worked well but the test is not passing.

The test passes when I don't use react-hook-form and jsut pass onSubmit <form onSubmit={onSubmit}>. As I pass onSubmit with handleSubmit <form onSubmit={handleSubmit(onSubmit)}>, it does not pass.

Here is my form App.js

import { useForm } from "react-hook-form";

export default function App({ onSubmit = (data) => console.log(data) }) {
  const { handleSubmit, register } = useForm();
  return (
    // <form onSubmit={onSubmit}>                  <--- This works
    // <form onSubmit={handleSubmit(onSubmit)}>    <--- This doesn't work
    <form onSubmit={handleSubmit(onSubmit)}>
      <input
        placeholder="Email"
        defaultValue=""
        key="email"
        {...register("email")}
      />
      <input
        placeholder="Password"
        defaultValue=""
        key="password"
        {...register("password")}
      />
      <input type="submit" value="submit" />
    </form>
  );
}

And here's the test I've written for it App.test.js

import { render, screen } from "@testing-library/react";
import App from "./App";
import userEvent from "@testing-library/user-event";

test("email and password field are clear for submit", async () => {
  const handleSubmit = jest.fn();

  render(<App onSubmit={handleSubmit} />);

  userEvent.type(screen.getByPlaceholderText(/email/i), "test@example.com");
  userEvent.type(screen.getByPlaceholderText(/password/i), "password");
  userEvent.click(screen.getByText(/submit/i));

  expect(handleSubmit).toHaveBeenCalledTimes(1);
});

Working code is also available at https://codesandbox.io/s/react-hook-form-testing-olo4i

Answer 1

handleSubmit has below the signature, as you can see, the return value of it is a promise. It's asynchronous.

That means calling it like this handleSubmit(onSubmit)(e) will return a promise.

type UseFormHandleSubmit<TFieldValues extends FieldValues> = <TSubmitFieldValues extends FieldValues = TFieldValues>(onValid: SubmitHandler<TSubmitFieldValues>, onInvalid?: SubmitErrorHandler<TFieldValues>) => (e?: React.BaseSyntheticEvent) => Promise<void>;

You need to use waitFor of RTL:

import { render, screen, waitFor } from "@testing-library/react";
import App from "./App";
import userEvent from "@testing-library/user-event";

test("email and password field are clear for submit", async () => {
  const handleSubmit = jest.fn();

  render(<App onSubmit={handleSubmit} />);

  userEvent.type(screen.getByPlaceholderText(/email/i), "test@example.com");
  userEvent.type(screen.getByPlaceholderText(/password/i), "password");
  userEvent.click(screen.getByText(/submit/i));

  await waitFor(() => {
    expect(handleSubmit).toHaveBeenCalledTimes(1);
  }) 
});

If you do not wait for the asynchronous code to complete, it may execute after the assertion ends.

Codesandbox

Reference source code