带有反应测试库的 Formik 表单提交

Question

我希望为 LoginForm 触发提交处理程序。但是，出于某种原因，组件的实际处理程序没有被调用，而是被调用（调用外部 api）。我怎样才能确保我的模拟处理程序被调用？

感兴趣的三个组件如下（演示、容器和测试套件）

LoginForm.js

import { Formik, Form, Field } from 'formik';
import { CustomInput } from '..';

const LoginForm = ({ initialValues, handleSubmit, validate }) => {
  return (
    <Formik
      initialValues={initialValues}
      validate={validate}
      onSubmit={handleSubmit}
    >
      {({ isSubmitting, handleSubmit }) => {
        return (
        <Form onSubmit={handleSubmit}>
          <div className="d-flex flex-column justify-content-center align-items-center">
            <Field
              data-testid="usernameOrEmail"
              type="text"
              name="identifier"
              placeholder="Username/Email"
              component={CustomInput}
              inputClass="mb-4 mt-2 text-monospace"
            />
            <Field
              data-testid="login-password"
              type="password"
              name="password"
              placeholder="Password"
              component={CustomInput}
              inputClass="mb-4 mt-4 text-monospace"
            />
            <button
              data-testid="login-button"
              className="btn btn-primary btn-lg mt-3 text-monospace"
              type="submit"
              disabled={isSubmitting}
              style={{ textTransform: 'uppercase', minWidth: '12rem' }}
            >
              Submit
            </button>
          </div>
        </Form>
      )}}
    </Formik>
  );
};

export default LoginForm;

LoginPage.js

import React, { useContext } from 'react';
import { loginUser } from '../../services';
import { userContext } from '../../contexts';
import { loginValidator } from '../../helpers';
import { setAuthorizationToken, renderAlert } from '../../utils';
import LoginForm from './login-form';

const INITIAL_VALUES = { identifier: '', password: '' };

const LoginPage = props => {
  const { handleUserData, handleAuthStatus } = useContext(userContext);

  const handleSubmit = async (values, { setSubmitting }) => {
    try {
      const result = await loginUser(values);
      handleAuthStatus(true);
      handleUserData(result.data);
      setAuthorizationToken(result.data.token);
      props.history.push('/habits');
      renderAlert('success', 'Login Successful');
    } catch (err) {
      renderAlert('error', err.message);
    }
    setSubmitting(false);
  };

  return (
    <LoginForm
      initialValues={INITIAL_VALUES}
      validate={values => loginValidator(values)}
      handleSubmit={handleSubmit}
    />
  );
};

export default LoginPage;

LoginPage.spec.js

import React from 'react';
import { cleanup, getByTestId, fireEvent, wait } from 'react-testing-library';
import { renderWithRouter } from '../../../helpers';
import LoginPage from '../login-page';

afterEach(cleanup);
const handleSubmit = jest.fn();

test('<LoginPage /> renders with blank fields', () => {
  const { container } = renderWithRouter(<LoginPage />);

  const usernameOrEmailNode = getByTestId(container, 'usernameOrEmail');
  const passwordNode = getByTestId(container, 'login-password');
  const submitButtonNode = getByTestId(container, 'login-button');

  expect(usernameOrEmailNode.tagName).toBe('INPUT');
  expect(passwordNode.tagName).toBe('INPUT');
  expect(submitButtonNode.tagName).toBe('BUTTON');
  expect(usernameOrEmailNode.getAttribute('value')).toBe('');
  expect(passwordNode.getAttribute('value')).toBe('');
});

test('Clicking the submit button after entering values', async () => {
  const { container } = renderWithRouter(<LoginPage handleSubmit={handleSubmit} />);

  const usernameOrEmailNode = getByTestId(container, 'usernameOrEmail');
  const passwordNode = getByTestId(container, 'login-password');
  const submitButtonNode = getByTestId(container, 'login-button');

  fireEvent.change(usernameOrEmailNode, { target: { value: fakeUser.username }});
  fireEvent.change(passwordNode, { target: { value: fakeUser.password }});
  fireEvent.click(submitButtonNode);

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


  expect(usernameOrEmailNode.tagName).toBe('INPUT');
  expect(passwordNode.tagName).toBe('INPUT');
  expect(submitButtonNode.tagName).toBe('BUTTON');
  expect(usernameOrEmailNode.getAttribute('value')).toBe('');
  expect(passwordNode.getAttribute('value')).toBe('');
});```

Answer 1

要回答您的问题，您需要首先使 handleSubmit 常量在 LoginPage.js 之外可访问，以便它可以被模拟然后进行测试。例如，

LoginPage.js

export const handleSubmit = async (values, { setSubmitting }) => {
 ... code to handle submission
})

在你的测试中 - LoginPage.spec.js

jest.unmock('./login-page');
import LoginPage, otherFunctions from '../login-page'
otherFunctions.handleSubmit = jest.fn();

...
test('Clicking the submit button after entering values', () => {
  ...
  fireEvent.click(submitButtonNode);
  expect(handleSubmit).toHaveBeenCalledTimes(1);
})

希望以上内容能解决您的问题。

But, going by the philosophy of unit testing, the above components must not be tested the way you are doing it. Instead your test setup should be like this -

Add a new test file called LoginForm.spec.js that tests your LoginForm component. You would test the following in this -

Check if all input fields have been rendered.

Check if the correct handler is called on submit and with the correct parameters.

The existing test file called LoginPage.spec.js would then only test if the particular form was rendered and then you could also test what the handleSubmit method does individually.

I believe the above would make your tests more clearer and readable too, because of the separation of concerns and would also allow you to test more edge cases.

带有反应测试库的 Formik 表单提交

Formik form submission with react-testing library

reactjs

formik

react-testing-library