useAutoScroll hook to enable React-Native screens to scroll to erroneous form fields

useAutoScroll.js

import React, { useRef } from 'react';
import { View, Dimensions } from 'react-native';
import util from 'helpers/util';

const useAutoScroll = () => {
  const yCoordinates = useRef({});
  let scrollRef = null;

  const setScrollRef = ref => {
    if (ref) scrollRef = ref;
  };

  const scrollTo = errors => {
    const firstInvalidKey = util.getFirstConditionalKey(yCoordinates.current, 'y', errors);
    if (yCoordinates.current[firstInvalidKey].ref) {
      yCoordinates.current[firstInvalidKey].ref.handleFocus({
        nativeEvent: { text: 'Dummy name' },
      });
    }

    scrollRef.scrollTo(0, yCoordinates.current[firstInvalidKey].y);
  };

  const captureRef = inputKey => ref => {
    if (ref) {
      if (yCoordinates.current[inputKey]) {
        yCoordinates.current[inputKey].ref = ref;
      } else {
        yCoordinates.current[inputKey] = {};
        yCoordinates.current[inputKey].ref = ref;
      }
    }
  };

  const scrollTracker = (component, inputKey) => {
    let viewRef;

    const getScrollToY = py => py - Dimensions.get('window').height / 5.5;

    const getCoordinates = () => {
      viewRef.measure((fx, fy, width, height, px, py) => {
        if (yCoordinates.current[inputKey]) {
          if (!yCoordinates.current[inputKey].y) {
            yCoordinates.current[inputKey].y = getScrollToY(py);
          }
        } else {
          yCoordinates.current[inputKey] = {};
          yCoordinates.current[inputKey].y = getScrollToY(py);
        }
      });
    };

    return (
      <View
        testID={`${inputKey}Wrapper`}
        /* eslint-disable-next-line no-return-assign */
        ref={ref => {
          if (ref) viewRef = ref;
        }}
        onLayout={getCoordinates}
      >
        {component}
      </View>
    );
  };

  return {
    scrollTracker,
    setScrollRef,
    scrollTo,
    captureRef,
  };
};

export default useAutoScroll;

useAutoScroll.test.js

import { Dimensions, Text, TextInput as RNTextInput, View as RNView } from 'react-native';
import { TextInput } from 'MyCustomTextInput';
import { fireEvent, flushMicrotasksQueue, render } from 'react-native-testing-library';
import React from 'react';
import useAutoScroll from './useAutoScroll';
import { renderHook } from '@testing-library/react-hooks';

describe('tests for useAutoScroll', () => {
  const mockFocus = jest.spyOn(RNTextInput.prototype, 'focus');
  const mockMeasure = jest.spyOn(RNView.prototype, 'measure');

  it('should render wrapperView', async () => {
    const { result } = renderHook(() => useAutoScroll());
    const { getByTestId } = render(result.current.scrollTracker(<Text>Noice</Text>, 'aNoiceKey'));
    await flushMicrotasksQueue();
    expect(getByTestId('aNoiceKeyWrapper')).toBeDefined();
  });

  it('should call scrollTo on click of button when yCoorodinate is absent while setting coordinate', () => {
    const mockScrollTo = jest.fn();
    const mockScrollRef = {
      scrollToPosition: mockScrollTo,
    };
    const { result } = renderHook(() => useAutoScroll());
    const { getByTestId } = render(
      result.current.scrollTracker(<TextInput ref={result.current.captureRef('aNoiceKey')} />, 'aNoiceKey')
    );
    fireEvent(getByTestId('aNoiceKeyWrapper'), 'onLayout');

    expect(mockMeasure).toHaveBeenCalledTimes(1);

    result.current.captureRef('aNoiceKey');
    fireEvent(getByTestId('aNoiceKeyWrapper'), 'onLayout');

    mockMeasure.mock.calls[0][0](23, 29, 31, 37, 89, 97);
    result.current.setScrollRef(mockScrollRef);
    result.current.scrollTo(['aNoiceKey']);
    expect(mockScrollTo).toHaveBeenCalledTimes(1);
    expect(mockScrollTo).toHaveBeenNthCalledWith(1, 0, 97 - Dimensions.get('window').height / 5.5);

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

  it('should call scrollTo on click of button when yCoordinate is absent during setting captureRef', () => {
    mockMeasure.mockClear();
    mockFocus.mockClear();
    let localRef = {};
    const mockScrollTo = jest.fn();
    const mockScrollRef = {
      scrollToPosition: mockScrollTo,
    };
    const { result } = renderHook(() => useAutoScroll());
    const { getByTestId } = render(
      // eslint-disable-next-line no-return-assign
      result.current.scrollTracker(<TextInput ref={ref => (localRef = ref)} />, 'aNoiceKey')
    );
    fireEvent(getByTestId('aNoiceKeyWrapper'), 'onLayout');

    expect(mockMeasure).toHaveBeenCalledTimes(1);
    mockMeasure.mock.calls[0][0](23, 29, 31, 37, 89, 97);

    result.current.captureRef('aNoiceKey')(localRef);

    result.current.setScrollRef(mockScrollRef);
    result.current.scrollTo(['aNoiceKey']);
    expect(mockScrollTo).toHaveBeenCalledTimes(1);
    expect(mockScrollTo).toHaveBeenNthCalledWith(1, 0, 97 - Dimensions.get('window').height / 5.5);

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

where i found util folder?

where I find the util folder?