panel_resizer_spec.js

import Vue from 'vue';
import panelResizer from '~/vue_shared/components/panel_resizer.vue';
import mountComponent from '../../helpers/vue_mount_component_helper';

describe('Panel Resizer component', () => {
  let vm;
  let PanelResizer;

  const triggerEvent = (eventName, el = vm.$el, clientX = 0) => {
    const event = document.createEvent('MouseEvents');
    event.initMouseEvent(eventName, true, true, window, 1, clientX, 0, clientX, 0, false, false,
                         false, false, 0, null);

    el.dispatchEvent(event);
  };

  beforeEach(() => {
    PanelResizer = Vue.extend(panelResizer);
  });

  afterEach(() => {
    vm.$destroy();
  });

  it('should render a div element with the correct classes and styles', () => {
    vm = mountComponent(PanelResizer, {
      startSize: 100,
      side: 'left',
    });

    expect(vm.$el.tagName).toEqual('DIV');
    expect(vm.$el.getAttribute('class')).toBe('dragHandle dragleft');
    expect(vm.$el.getAttribute('style')).toBe('cursor: ew-resize;');
  });

  it('should render a div element with the correct classes for a right side panel', () => {
    vm = mountComponent(PanelResizer, {
      startSize: 100,
      side: 'right',
    });

    expect(vm.$el.tagName).toEqual('DIV');
    expect(vm.$el.getAttribute('class')).toBe('dragHandle dragright');
  });

  it('drag the resizer', () => {
    vm = mountComponent(PanelResizer, {
      startSize: 100,
      side: 'left',
    });

    spyOn(vm, '$emit');
    triggerEvent('mousedown', vm.$el);
    triggerEvent('mousemove', document);
    triggerEvent('mouseup', document);
    expect(vm.$emit.calls.allArgs()).toEqual([['resize-start', 100], ['update:size', 100], ['resize-end', 100]]);
    expect(vm.size).toBe(100);
  });
});