如何在Angular单元测试里，对class protected方法进行测试

import { Injectable } from '@angular/core';
import { TestBed } from '@angular/core/testing';
import { EntitiesModel } from '@spartacus/core';
import {
  B2BUnitNode,
  B2BUnitTreeNode,
  OrgUnitService,
} from '@spartacus/organization/administration/core';
import { TableService, TableStructure } from '@spartacus/storefront';
import { BehaviorSubject, Observable, of } from 'rxjs';
import { UnitItemService } from './unit-item.service';
import { UnitListService } from './unit-list.service';
import { TREE_TOGGLE } from './unit-tree.model';
import { UnitTreeService } from './unit-tree.service';
import createSpy = jasmine.createSpy;
function verifyExpandedAll({ values }: EntitiesModel<B2BUnitTreeNode>) {
  expect(values.length).toEqual(7);
  values.forEach((element) => {
    expect(element.expanded).toBeTrue();
  });
}
function verifyCollapsedAll({ values }: EntitiesModel<B2BUnitTreeNode>) {
  const root = values[0];
  expect(values.length).toEqual(1);
  expect(root.uid).toEqual(mockedTree.id);
  expect(root.expanded).toBeFalse();
  expect(root.depthLevel).toEqual(0);
  expect(root.count).toEqual(mockedTree.children.length);
}
const codeKey = 'uid';
const mockedTree = {
  id: 'Rustic',
  name: 'Rustic',
  active: true,
  children: [
    {
      id: 'Rustic Services',
      name: 'Rustic Services',
      parent: 'Rustic',
      active: true,
      children: [
        {
          active: true,
          children: [],
          id: 'Services West',
          name: 'Services West',
          parent: 'Rustic Services',
        },
        {
          active: true,
          children: [],
          id: 'Services East',
          name: 'Services East',
          parent: 'Rustic Services',
        },
      ],
    },
    {
      id: 'Rustic Retail',
      name: 'Rustic Retail',
      parent: 'Rustic',
      active: true,
      children: [
        {
          active: true,
          id: 'Custom Retail',
          name: 'Custom Retail',
          parent: 'Rustic Retail',
          children: [
            {
              active: true,
              children: [],
              id: 'Test',
              name: 'TestUnit',
              parent: 'Custom Retail',
            },
          ],
        },
      ],
    },
  ],
};
const mockedTreeBeforeConvert = {
  id: 'Rustic',
  name: 'Rustic',
  active: true,
  children: [
    {
      id: 'test3',
      name: 'test3',
      parent: 'Rustic',
      active: true,
      children: [],
    },
    {
      id: 'test1',
      name: 'test1',
      parent: 'Rustic',
      active: true,
      children: [],
    },
    {
      id: 'test2',
      name: 'test2',
      parent: 'Rustic',
      active: true,
      children: [],
    },
  ],
};
const mockedTreeAfterConvert = {
  pagination: {
    totalResults: 4,
  },
  values: [
    {
      active: true,
      children: [
        {
          id: 'test1',
          name: 'test1',
          parent: 'Rustic',
          active: true,
          children: [],
        },
        {
          id: 'test2',
          name: 'test2',
          parent: 'Rustic',
          active: true,
          children: [],
        },
        {
          id: 'test3',
          name: 'test3',
          parent: 'Rustic',
          active: true,
          children: [],
        },
      ],
      count: 3,
      depthLevel: 0,
      expanded: false,
      id: 'Rustic',
      name: 'Rustic',
      uid: 'Rustic',
    },
  ],
};
const treeToggle$ = new BehaviorSubject(
  new Map().set(mockedTree.id, TREE_TOGGLE.EXPANDED)
);
class MockUnitService {
  getTree(): Observable<B2BUnitNode> {
    return of(mockedTree);
  }
}
@Injectable()
export class MockTableService {
  buildStructure(type): Observable<TableStructure> {
    return of({ type });
  }
}
export class MockUnitTreeService {
  treeToggle$ = treeToggle$.asObservable();
  initialize = createSpy('initialize');
  getToggleState = createSpy('getToggleState')
    .withArgs(mockedTree.id)
    .and.returnValue(treeToggle$.value?.get(mockedTree.id));
  isExpanded = createSpy('isExpanded').and.returnValue(false);
}
export class UnitListServiceForSortTest extends UnitListService {
  public convertListItemWrapper(unit: B2BUnitNode) {
    return this.convertListItem(unit);
  }
}
describe('UnitListService', () => {
  let service: UnitListService;
  let treeService: UnitTreeService;
  describe('with table config', () => {
    beforeEach(() => {
      TestBed.configureTestingModule({
        providers: [
          {
            provide: UnitListService,
            useClass: UnitListServiceForSortTest,
          },
          {
            provide: UnitTreeService,
            useClass: MockUnitTreeService,
          },
          {
            provide: OrgUnitService,
            useClass: MockUnitService,
          },
          {
            provide: TableService,
            useClass: MockTableService,
          },
          {
            provide: UnitItemService,
            useValue: {
              key$: of(mockedTree.id),
            },
          },
        ],
      });
      service = TestBed.inject(UnitListService);
      treeService = TestBed.inject(UnitTreeService);
    });
    it('should inject service', () => {
      expect(service).toBeTruthy();
    });
    it('should return "code" key', () => {
      expect(service.key()).toEqual(codeKey);
    });
    it('should get collapsed all items structure', () => {
      let result: EntitiesModel<B2BUnitTreeNode>;
      service.getData().subscribe((table) => (result = table));
      verifyCollapsedAll(result);
    });
    it('should get expanded all items structure', () => {
      let result: EntitiesModel<B2BUnitTreeNode>;
      treeService.isExpanded = createSpy().and.returnValue(true);
      service.getData().subscribe((table) => (result = table));
      verifyExpandedAll(result);
    });
    it('should automatically sort unit tree by name', () => {
      const serviceForSort = service as UnitListServiceForSortTest;
      const convertedTree = serviceForSort.convertListItemWrapper(
        mockedTreeBeforeConvert
      );
      expect(convertedTree).toEqual(mockedTreeAfterConvert);
    });
  });
});