react-infinite/__tests__/array_infinite_computer_test.js

A browser-ready efficient scrolling container based on UITableView

/* eslint-env jest */

jest.dontMock('../src/utils/binaryIndexSearch.js');
jest.dontMock('../src/computers/arrayInfiniteComputer.js');
jest.dontMock('../src/computers/infiniteComputer.js');

var ArrayInfiniteComputer = require('../src/computers/arrayInfiniteComputer.js');

describe('Array Infinite Computer', () => {
  describe('getTotalScrollableHeight()', () => {
    it('provides the correct sum of its children', () => {
      var aic = new ArrayInfiniteComputer([10, 20, 40, 80], 0);
      expect(aic.getTotalScrollableHeight()).toEqual(150);
    });

    it('provides the correct mixed sum of its children', () => {
      var aic = new ArrayInfiniteComputer([10, 140, 12, 10, 204], 0);
      expect(aic.getTotalScrollableHeight()).toEqual(376);
    });

    it('provides the correct constant sum of its children', () => {
      var aic = new ArrayInfiniteComputer([100, 100, 100, 100], 0);
      expect(aic.getTotalScrollableHeight()).toEqual(400);
    });

    it('provides the correct empty sum of its children', () => {
      var aic = new ArrayInfiniteComputer([], 0);
      expect(aic.getTotalScrollableHeight()).toEqual(0);
    });
  });

  describe('getDisplayIndexStart()', () => {
    it('computes the correct display index when precisely at element border', () => {
      var aic = new ArrayInfiniteComputer(
        [20, 30, 40, 50, 60, 70, 80, 90, 100],
        8
      );
      expect(aic.getDisplayIndexStart(200)).toEqual(4);
    });

    it('computes the correct display index when not precisely at element border', () => {
      var aic = new ArrayInfiniteComputer(
        [20, 30, 40, 50, 60, 70, 80, 90, 100],
        8
      );
      expect(aic.getDisplayIndexStart(130)).toEqual(3);
    });

    it('computes a zero display index correctly', () => {
      var aic = new ArrayInfiniteComputer(
        [20, 30, 40, 50, 60, 70, 80, 90, 100],
        8
      );
      expect(aic.getDisplayIndexStart(0)).toEqual(0);
    });

    it('computes a zero display index correctly with one array element', () => {
      var aic = new ArrayInfiniteComputer([20], 1);
      expect(aic.getDisplayIndexStart(10)).toEqual(0);
    });
    it('returns -1 when there are no items', () => {
      var aic = new ArrayInfiniteComputer([], 0);
      expect(aic.getDisplayIndexStart(800)).toEqual(-1);
      expect(aic.getDisplayIndexStart(0)).toEqual(-1);
    });
  });

  describe('getDisplayIndexEnd()', () => {
    it('computes the correct display index when precisely at element border', () => {
      var aic = new ArrayInfiniteComputer([130, 120, 110, 100, 90, 80, 70], 7);
      expect(aic.getDisplayIndexEnd(550)).toEqual(4);
    });

    it('computes the correct display index when not precisely at element border', () => {
      var aic = new ArrayInfiniteComputer([130, 120, 110, 100, 90, 80, 70], 7);
      expect(aic.getDisplayIndexEnd(444)).toEqual(3);
    });

    it('computes the correct end index when all items fit within the container', () => {
      var aic = new ArrayInfiniteComputer([28], 1);
      expect(aic.getDisplayIndexEnd(627)).toEqual(0);

      aic = new ArrayInfiniteComputer([28, 28, 28, 10], 4);
      expect(aic.getDisplayIndexEnd(627)).toEqual(3);
    });

    it('returns -1 when there are no items', () => {
      var aic = new ArrayInfiniteComputer([], 0);
      expect(aic.getDisplayIndexEnd(800)).toEqual(-1);
      expect(aic.getDisplayIndexEnd(0)).toEqual(-1);
    });

    // xit('computes indexes correctly with zero-height elements', () => {});
  });

  describe('getTopSpacerHeight()', () => {
    it('correctly computes a zero top spacer height', () => {
      var aic = new ArrayInfiniteComputer([40, 80, 160, 320], 4);
      expect(aic.getTopSpacerHeight(0)).toEqual(0);
    });

    it('correctly computes a regular top spacer height', () => {
      var aic = new ArrayInfiniteComputer([40, 80, 160, 320], 4);
      expect(aic.getTopSpacerHeight(1)).toEqual(40);
      expect(aic.getTopSpacerHeight(2)).toEqual(120);
      expect(aic.getTopSpacerHeight(3)).toEqual(280);
    });
  });

  describe('getBottomSpacerHeight()', () => {
    it('correctly computes a bottom spacer height when the last item is rendered', () => {
      var aic = new ArrayInfiniteComputer([20, 40, 80, 160], 4);
      expect(aic.getBottomSpacerHeight(3)).toEqual(0);
    });

    it('correctly computes a regular bottom spacer height', () => {
      var aic = new ArrayInfiniteComputer([20, 40, 80, 160], 4);
      expect(aic.getBottomSpacerHeight(0)).toEqual(280);
      expect(aic.getBottomSpacerHeight(1)).toEqual(240);
      expect(aic.getBottomSpacerHeight(2)).toEqual(160);
    });

    it('correctly computes bottom spacer height when there are no items', () => {
      var aic = new ArrayInfiniteComputer([], 0);
      expect(aic.getBottomSpacerHeight(-1)).toEqual(0);
    });
  });
});