react-test/test/regressions/fixtures/Button/FullWidthLoadingButtons.js

import * as React from 'react';
import Button from '@mui/material/Button';
import FormControlLabel from '@mui/material/FormControlLabel';
import Switch from '@mui/material/Switch';
import SaveIcon from '@mui/icons-material/Save';
import SendIcon from '@mui/icons-material/Send';

export default function FullWidthLoadingButtonsTransition() {
  const [loading, setLoading] = React.useState(true);
  function handleClick() {
    setLoading(true);
  }

  return (
    <div>
      <FormControlLabel
        sx={{
          display: 'block',
        }}
        control={
          <Switch
            checked={loading}
            onChange={() => setLoading(!loading)}
            name="loading"
            color="primary"
          />
        }
        label="Loading"
      />
      <Button onClick={handleClick} loading={loading} variant="outlined" fullWidth>
        Fetch data
      </Button>
      <Button
        onClick={handleClick}
        endIcon={<SendIcon />}
        loading={loading}
        loadingPosition="end"
        variant="contained"
        fullWidth
      >
        Send
      </Button>
      <Button
        color="secondary"
        onClick={handleClick}
        loading={loading}
        loadingPosition="start"
        startIcon={<SaveIcon />}
        variant="contained"
        fullWidth
      >
        Save
      </Button>
    </div>
  );
}